[InstCombine] Simplify nonnull pointers #128111
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@llvm/pr-subscribers-llvm-ir Author: Yingwei Zheng (dtcxzyw) ChangesThis patch is the follow-up of #127979. It introduces a helper Based on #128107. Full diff: https://github.com/llvm/llvm-project/pull/128111.diff 9 Files Affected:
diff --git a/llvm/include/llvm/IR/Function.h b/llvm/include/llvm/IR/Function.h
index 29041688124bc..7ea8673bedad1 100644
--- a/llvm/include/llvm/IR/Function.h
+++ b/llvm/include/llvm/IR/Function.h
@@ -731,6 +731,11 @@ class LLVM_ABI Function : public GlobalObject, public ilist_node<Function> {
/// create a Function) from the Function Src to this one.
void copyAttributesFrom(const Function *Src);
+ /// Return true if the return value is known to be not null.
+ /// This may be because it has the nonnull attribute, or because at least
+ /// one byte is dereferenceable and the pointer is in addrspace(0).
+ bool isReturnNonNull() const;
+
/// deleteBody - This method deletes the body of the function, and converts
/// the linkage to external.
///
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 5666f0a53866f..d22cf65769e26 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -873,6 +873,17 @@ void Function::copyAttributesFrom(const Function *Src) {
setPrologueData(Src->getPrologueData());
}
+bool Function::isReturnNonNull() const {
+ if (hasRetAttribute(Attribute::NonNull))
+ return true;
+
+ if (AttributeSets.getRetDereferenceableBytes() > 0 &&
+ !NullPointerIsDefined(this, getReturnType()->getPointerAddressSpace()))
+ return true;
+
+ return false;
+}
+
MemoryEffects Function::getMemoryEffects() const {
return getAttributes().getMemoryEffects();
}
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 400ebcf493713..c8b3d29c3aa98 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -3993,10 +3993,20 @@ Instruction *InstCombinerImpl::visitCallBase(CallBase &Call) {
unsigned ArgNo = 0;
for (Value *V : Call.args()) {
- if (V->getType()->isPointerTy() &&
- !Call.paramHasAttr(ArgNo, Attribute::NonNull) &&
- isKnownNonZero(V, getSimplifyQuery().getWithInstruction(&Call)))
- ArgNos.push_back(ArgNo);
+ if (V->getType()->isPointerTy()) {
+ // Simplify the nonnull operand before nonnull inference to avoid
+ // unnecessary queries.
+ if (Call.paramHasNonNullAttr(ArgNo, /*AllowUndefOrPoison=*/true)) {
+ if (Value *Res = simplifyNonNullOperand(V)) {
+ replaceOperand(Call, ArgNo, Res);
+ Changed = true;
+ }
+ }
+
+ if (!Call.paramHasAttr(ArgNo, Attribute::NonNull) &&
+ isKnownNonZero(V, getSimplifyQuery().getWithInstruction(&Call)))
+ ArgNos.push_back(ArgNo);
+ }
ArgNo++;
}
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index 83e1da98deeda..71c80d4c401f8 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -455,6 +455,10 @@ class LLVM_LIBRARY_VISIBILITY InstCombinerImpl final
Instruction *hoistFNegAboveFMulFDiv(Value *FNegOp, Instruction &FMFSource);
+ /// Simplify \p V given that it is known to be non-null.
+ /// Returns the simplified value if possible, otherwise returns nullptr.
+ Value *simplifyNonNullOperand(Value *V);
+
public:
/// Create and insert the idiom we use to indicate a block is unreachable
/// without having to rewrite the CFG from within InstCombine.
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index d5534c15cca76..89fc1051b18dc 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -982,6 +982,19 @@ static bool canSimplifyNullLoadOrGEP(LoadInst &LI, Value *Op) {
return false;
}
+/// TODO: Recursively simplify nonnull value to handle one-use inbounds GEPs.
+Value *InstCombinerImpl::simplifyNonNullOperand(Value *V) {
+ if (auto *Sel = dyn_cast<SelectInst>(V)) {
+ if (isa<ConstantPointerNull>(Sel->getOperand(1)))
+ return Sel->getOperand(2);
+
+ if (isa<ConstantPointerNull>(Sel->getOperand(2)))
+ return Sel->getOperand(1);
+ }
+
+ return nullptr;
+}
+
Instruction *InstCombinerImpl::visitLoadInst(LoadInst &LI) {
Value *Op = LI.getOperand(0);
if (Value *Res = simplifyLoadInst(&LI, Op, SQ.getWithInstruction(&LI)))
@@ -1059,20 +1072,13 @@ Instruction *InstCombinerImpl::visitLoadInst(LoadInst &LI) {
V2->copyMetadata(LI, Metadata::PoisonGeneratingIDs);
return SelectInst::Create(SI->getCondition(), V1, V2);
}
-
- // load (select (cond, null, P)) -> load P
- if (isa<ConstantPointerNull>(SI->getOperand(1)) &&
- !NullPointerIsDefined(SI->getFunction(),
- LI.getPointerAddressSpace()))
- return replaceOperand(LI, 0, SI->getOperand(2));
-
- // load (select (cond, P, null)) -> load P
- if (isa<ConstantPointerNull>(SI->getOperand(2)) &&
- !NullPointerIsDefined(SI->getFunction(),
- LI.getPointerAddressSpace()))
- return replaceOperand(LI, 0, SI->getOperand(1));
}
}
+
+ if (!NullPointerIsDefined(LI.getFunction(), LI.getPointerAddressSpace()))
+ if (Value *V = simplifyNonNullOperand(Op))
+ return replaceOperand(LI, 0, V);
+
return nullptr;
}
@@ -1437,19 +1443,9 @@ Instruction *InstCombinerImpl::visitStoreInst(StoreInst &SI) {
if (isa<UndefValue>(Val))
return eraseInstFromFunction(SI);
- // TODO: Add a helper to simplify the pointer operand for all memory
- // instructions.
- // store val, (select (cond, null, P)) -> store val, P
- // store val, (select (cond, P, null)) -> store val, P
- if (!NullPointerIsDefined(SI.getFunction(), SI.getPointerAddressSpace())) {
- if (SelectInst *Sel = dyn_cast<SelectInst>(Ptr)) {
- if (isa<ConstantPointerNull>(Sel->getOperand(1)))
- return replaceOperand(SI, 1, Sel->getOperand(2));
-
- if (isa<ConstantPointerNull>(Sel->getOperand(2)))
- return replaceOperand(SI, 1, Sel->getOperand(1));
- }
- }
+ if (!NullPointerIsDefined(SI.getFunction(), SI.getPointerAddressSpace()))
+ if (Value *V = simplifyNonNullOperand(Ptr))
+ return replaceOperand(SI, 1, V);
return nullptr;
}
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 5621511570b58..d3af06f63fcd2 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -3587,7 +3587,15 @@ Instruction *InstCombinerImpl::visitFree(CallInst &FI, Value *Op) {
Instruction *InstCombinerImpl::visitReturnInst(ReturnInst &RI) {
Value *RetVal = RI.getReturnValue();
- if (!RetVal || !AttributeFuncs::isNoFPClassCompatibleType(RetVal->getType()))
+ if (!RetVal)
+ return nullptr;
+
+ if (RetVal->getType()->isPointerTy() && RI.getFunction()->isReturnNonNull()) {
+ if (Value *V = simplifyNonNullOperand(RetVal))
+ return replaceOperand(RI, 0, V);
+ }
+
+ if (!AttributeFuncs::isNoFPClassCompatibleType(RetVal->getType()))
return nullptr;
Function *F = RI.getFunction();
diff --git a/llvm/test/Transforms/InstCombine/nonnull-select.ll b/llvm/test/Transforms/InstCombine/nonnull-select.ll
index 3fab2dfb41a42..cc000b4c88164 100644
--- a/llvm/test/Transforms/InstCombine/nonnull-select.ll
+++ b/llvm/test/Transforms/InstCombine/nonnull-select.ll
@@ -5,10 +5,7 @@
define nonnull ptr @pr48975(ptr %.0) {
; CHECK-LABEL: @pr48975(
-; CHECK-NEXT: [[DOT1:%.*]] = load ptr, ptr [[DOT0:%.*]], align 8
-; CHECK-NEXT: [[DOT2:%.*]] = icmp eq ptr [[DOT1]], null
-; CHECK-NEXT: [[DOT4:%.*]] = select i1 [[DOT2]], ptr null, ptr [[DOT0]]
-; CHECK-NEXT: ret ptr [[DOT4]]
+; CHECK-NEXT: ret ptr [[DOT4:%.*]]
;
%.1 = load ptr, ptr %.0, align 8
%.2 = icmp eq ptr %.1, null
@@ -18,8 +15,7 @@ define nonnull ptr @pr48975(ptr %.0) {
define nonnull ptr @nonnull_ret(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_ret(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr [[P:%.*]], ptr null
-; CHECK-NEXT: ret ptr [[RES]]
+; CHECK-NEXT: ret ptr [[RES:%.*]]
;
%res = select i1 %cond, ptr %p, ptr null
ret ptr %res
@@ -27,8 +23,7 @@ define nonnull ptr @nonnull_ret(i1 %cond, ptr %p) {
define nonnull ptr @nonnull_ret2(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_ret2(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr null, ptr [[P:%.*]]
-; CHECK-NEXT: ret ptr [[RES]]
+; CHECK-NEXT: ret ptr [[RES:%.*]]
;
%res = select i1 %cond, ptr null, ptr %p
ret ptr %res
@@ -36,8 +31,7 @@ define nonnull ptr @nonnull_ret2(i1 %cond, ptr %p) {
define nonnull noundef ptr @nonnull_noundef_ret(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_noundef_ret(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr [[P:%.*]], ptr null
-; CHECK-NEXT: ret ptr [[RES]]
+; CHECK-NEXT: ret ptr [[RES:%.*]]
;
%res = select i1 %cond, ptr %p, ptr null
ret ptr %res
@@ -45,8 +39,7 @@ define nonnull noundef ptr @nonnull_noundef_ret(i1 %cond, ptr %p) {
define nonnull noundef ptr @nonnull_noundef_ret2(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_noundef_ret2(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr null, ptr [[P:%.*]]
-; CHECK-NEXT: ret ptr [[RES]]
+; CHECK-NEXT: ret ptr [[RES:%.*]]
;
%res = select i1 %cond, ptr null, ptr %p
ret ptr %res
@@ -55,8 +48,7 @@ define nonnull noundef ptr @nonnull_noundef_ret2(i1 %cond, ptr %p) {
define void @nonnull_call(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_call(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr [[P:%.*]], ptr null
-; CHECK-NEXT: call void @f(ptr nonnull [[RES]])
+; CHECK-NEXT: call void @f(ptr nonnull [[RES:%.*]])
; CHECK-NEXT: ret void
;
%res = select i1 %cond, ptr %p, ptr null
@@ -66,8 +58,7 @@ define void @nonnull_call(i1 %cond, ptr %p) {
define void @nonnull_call2(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_call2(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr null, ptr [[P:%.*]]
-; CHECK-NEXT: call void @f(ptr nonnull [[RES]])
+; CHECK-NEXT: call void @f(ptr nonnull [[RES:%.*]])
; CHECK-NEXT: ret void
;
%res = select i1 %cond, ptr null, ptr %p
@@ -77,8 +68,7 @@ define void @nonnull_call2(i1 %cond, ptr %p) {
define void @nonnull_noundef_call(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_noundef_call(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr [[P:%.*]], ptr null
-; CHECK-NEXT: call void @f(ptr noundef nonnull [[RES]])
+; CHECK-NEXT: call void @f(ptr noundef nonnull [[RES:%.*]])
; CHECK-NEXT: ret void
;
%res = select i1 %cond, ptr %p, ptr null
@@ -88,8 +78,7 @@ define void @nonnull_noundef_call(i1 %cond, ptr %p) {
define void @nonnull_noundef_call2(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_noundef_call2(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr null, ptr [[P:%.*]]
-; CHECK-NEXT: call void @f(ptr noundef nonnull [[RES]])
+; CHECK-NEXT: call void @f(ptr noundef nonnull [[RES:%.*]])
; CHECK-NEXT: ret void
;
%res = select i1 %cond, ptr null, ptr %p
diff --git a/llvm/test/Transforms/PhaseOrdering/load-store-sameval.ll b/llvm/test/Transforms/PhaseOrdering/load-store-sameval.ll
index d8ef0723cf09e..f6bf57a678786 100644
--- a/llvm/test/Transforms/PhaseOrdering/load-store-sameval.ll
+++ b/llvm/test/Transforms/PhaseOrdering/load-store-sameval.ll
@@ -1,24 +1,21 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -passes='instcombine,early-cse<memssa>' -S %s | FileCheck %s
-; FIXME: We can remove the store instruction in the exit block
define i32 @load_store_sameval(ptr %p, i1 %cond1, i1 %cond2) {
; CHECK-LABEL: define i32 @load_store_sameval(
; CHECK-SAME: ptr [[P:%.*]], i1 [[COND1:%.*]], i1 [[COND2:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
-; CHECK-NEXT: [[SPEC_SELECT:%.*]] = select i1 [[COND1]], ptr null, ptr [[P]]
-; CHECK-NEXT: [[PRE:%.*]] = load i32, ptr [[SPEC_SELECT]], align 4
+; CHECK-NEXT: [[PRE:%.*]] = load i32, ptr [[P]], align 4
; CHECK-NEXT: br label %[[BLOCK:.*]]
; CHECK: [[BLOCK]]:
; CHECK-NEXT: br label %[[BLOCK2:.*]]
; CHECK: [[BLOCK2]]:
; CHECK-NEXT: br i1 [[COND2]], label %[[BLOCK3:.*]], label %[[EXIT:.*]]
; CHECK: [[BLOCK3]]:
-; CHECK-NEXT: [[LOAD:%.*]] = load double, ptr [[SPEC_SELECT]], align 8
+; CHECK-NEXT: [[LOAD:%.*]] = load double, ptr [[P]], align 8
; CHECK-NEXT: [[CMP:%.*]] = fcmp une double [[LOAD]], 0.000000e+00
; CHECK-NEXT: br i1 [[CMP]], label %[[BLOCK]], label %[[BLOCK2]]
; CHECK: [[EXIT]]:
-; CHECK-NEXT: store i32 [[PRE]], ptr [[P]], align 4
; CHECK-NEXT: ret i32 0
;
entry:
diff --git a/llvm/test/Transforms/PhaseOrdering/memset-combine.ll b/llvm/test/Transforms/PhaseOrdering/memset-combine.ll
new file mode 100644
index 0000000000000..d1de11258ed91
--- /dev/null
+++ b/llvm/test/Transforms/PhaseOrdering/memset-combine.ll
@@ -0,0 +1,20 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+
+; RUN: opt < %s -passes=instcombine,memcpyopt -S | FileCheck %s
+
+; FIXME: These two memset calls should be merged into a single one.
+define void @merge_memset(ptr %p, i1 %cond) {
+; CHECK-LABEL: define void @merge_memset(
+; CHECK-SAME: ptr [[P:%.*]], i1 [[COND:%.*]]) {
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[COND]], ptr null, ptr [[P]]
+; CHECK-NEXT: tail call void @llvm.memset.p0.i64(ptr noundef nonnull align 1 dereferenceable(4096) [[P]], i8 0, i64 4096, i1 false)
+; CHECK-NEXT: [[OFF:%.*]] = getelementptr inbounds nuw i8, ptr [[SEL]], i64 4096
+; CHECK-NEXT: tail call void @llvm.memset.p0.i64(ptr noundef nonnull align 1 dereferenceable(768) [[OFF]], i8 0, i64 768, i1 false)
+; CHECK-NEXT: ret void
+;
+ %sel = select i1 %cond, ptr null, ptr %p
+ tail call void @llvm.memset.p0.i64(ptr noundef nonnull %sel, i8 0, i64 4096, i1 false)
+ %off = getelementptr inbounds nuw i8, ptr %sel, i64 4096
+ tail call void @llvm.memset.p0.i64(ptr noundef nonnull %off, i8 0, i64 768, i1 false)
+ ret void
+}
|
|
@llvm/pr-subscribers-llvm-transforms Author: Yingwei Zheng (dtcxzyw) ChangesThis patch is the follow-up of #127979. It introduces a helper Based on #128107. Full diff: https://github.com/llvm/llvm-project/pull/128111.diff 9 Files Affected:
diff --git a/llvm/include/llvm/IR/Function.h b/llvm/include/llvm/IR/Function.h
index 29041688124bc..7ea8673bedad1 100644
--- a/llvm/include/llvm/IR/Function.h
+++ b/llvm/include/llvm/IR/Function.h
@@ -731,6 +731,11 @@ class LLVM_ABI Function : public GlobalObject, public ilist_node<Function> {
/// create a Function) from the Function Src to this one.
void copyAttributesFrom(const Function *Src);
+ /// Return true if the return value is known to be not null.
+ /// This may be because it has the nonnull attribute, or because at least
+ /// one byte is dereferenceable and the pointer is in addrspace(0).
+ bool isReturnNonNull() const;
+
/// deleteBody - This method deletes the body of the function, and converts
/// the linkage to external.
///
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 5666f0a53866f..d22cf65769e26 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -873,6 +873,17 @@ void Function::copyAttributesFrom(const Function *Src) {
setPrologueData(Src->getPrologueData());
}
+bool Function::isReturnNonNull() const {
+ if (hasRetAttribute(Attribute::NonNull))
+ return true;
+
+ if (AttributeSets.getRetDereferenceableBytes() > 0 &&
+ !NullPointerIsDefined(this, getReturnType()->getPointerAddressSpace()))
+ return true;
+
+ return false;
+}
+
MemoryEffects Function::getMemoryEffects() const {
return getAttributes().getMemoryEffects();
}
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 400ebcf493713..c8b3d29c3aa98 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -3993,10 +3993,20 @@ Instruction *InstCombinerImpl::visitCallBase(CallBase &Call) {
unsigned ArgNo = 0;
for (Value *V : Call.args()) {
- if (V->getType()->isPointerTy() &&
- !Call.paramHasAttr(ArgNo, Attribute::NonNull) &&
- isKnownNonZero(V, getSimplifyQuery().getWithInstruction(&Call)))
- ArgNos.push_back(ArgNo);
+ if (V->getType()->isPointerTy()) {
+ // Simplify the nonnull operand before nonnull inference to avoid
+ // unnecessary queries.
+ if (Call.paramHasNonNullAttr(ArgNo, /*AllowUndefOrPoison=*/true)) {
+ if (Value *Res = simplifyNonNullOperand(V)) {
+ replaceOperand(Call, ArgNo, Res);
+ Changed = true;
+ }
+ }
+
+ if (!Call.paramHasAttr(ArgNo, Attribute::NonNull) &&
+ isKnownNonZero(V, getSimplifyQuery().getWithInstruction(&Call)))
+ ArgNos.push_back(ArgNo);
+ }
ArgNo++;
}
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index 83e1da98deeda..71c80d4c401f8 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -455,6 +455,10 @@ class LLVM_LIBRARY_VISIBILITY InstCombinerImpl final
Instruction *hoistFNegAboveFMulFDiv(Value *FNegOp, Instruction &FMFSource);
+ /// Simplify \p V given that it is known to be non-null.
+ /// Returns the simplified value if possible, otherwise returns nullptr.
+ Value *simplifyNonNullOperand(Value *V);
+
public:
/// Create and insert the idiom we use to indicate a block is unreachable
/// without having to rewrite the CFG from within InstCombine.
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index d5534c15cca76..89fc1051b18dc 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -982,6 +982,19 @@ static bool canSimplifyNullLoadOrGEP(LoadInst &LI, Value *Op) {
return false;
}
+/// TODO: Recursively simplify nonnull value to handle one-use inbounds GEPs.
+Value *InstCombinerImpl::simplifyNonNullOperand(Value *V) {
+ if (auto *Sel = dyn_cast<SelectInst>(V)) {
+ if (isa<ConstantPointerNull>(Sel->getOperand(1)))
+ return Sel->getOperand(2);
+
+ if (isa<ConstantPointerNull>(Sel->getOperand(2)))
+ return Sel->getOperand(1);
+ }
+
+ return nullptr;
+}
+
Instruction *InstCombinerImpl::visitLoadInst(LoadInst &LI) {
Value *Op = LI.getOperand(0);
if (Value *Res = simplifyLoadInst(&LI, Op, SQ.getWithInstruction(&LI)))
@@ -1059,20 +1072,13 @@ Instruction *InstCombinerImpl::visitLoadInst(LoadInst &LI) {
V2->copyMetadata(LI, Metadata::PoisonGeneratingIDs);
return SelectInst::Create(SI->getCondition(), V1, V2);
}
-
- // load (select (cond, null, P)) -> load P
- if (isa<ConstantPointerNull>(SI->getOperand(1)) &&
- !NullPointerIsDefined(SI->getFunction(),
- LI.getPointerAddressSpace()))
- return replaceOperand(LI, 0, SI->getOperand(2));
-
- // load (select (cond, P, null)) -> load P
- if (isa<ConstantPointerNull>(SI->getOperand(2)) &&
- !NullPointerIsDefined(SI->getFunction(),
- LI.getPointerAddressSpace()))
- return replaceOperand(LI, 0, SI->getOperand(1));
}
}
+
+ if (!NullPointerIsDefined(LI.getFunction(), LI.getPointerAddressSpace()))
+ if (Value *V = simplifyNonNullOperand(Op))
+ return replaceOperand(LI, 0, V);
+
return nullptr;
}
@@ -1437,19 +1443,9 @@ Instruction *InstCombinerImpl::visitStoreInst(StoreInst &SI) {
if (isa<UndefValue>(Val))
return eraseInstFromFunction(SI);
- // TODO: Add a helper to simplify the pointer operand for all memory
- // instructions.
- // store val, (select (cond, null, P)) -> store val, P
- // store val, (select (cond, P, null)) -> store val, P
- if (!NullPointerIsDefined(SI.getFunction(), SI.getPointerAddressSpace())) {
- if (SelectInst *Sel = dyn_cast<SelectInst>(Ptr)) {
- if (isa<ConstantPointerNull>(Sel->getOperand(1)))
- return replaceOperand(SI, 1, Sel->getOperand(2));
-
- if (isa<ConstantPointerNull>(Sel->getOperand(2)))
- return replaceOperand(SI, 1, Sel->getOperand(1));
- }
- }
+ if (!NullPointerIsDefined(SI.getFunction(), SI.getPointerAddressSpace()))
+ if (Value *V = simplifyNonNullOperand(Ptr))
+ return replaceOperand(SI, 1, V);
return nullptr;
}
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 5621511570b58..d3af06f63fcd2 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -3587,7 +3587,15 @@ Instruction *InstCombinerImpl::visitFree(CallInst &FI, Value *Op) {
Instruction *InstCombinerImpl::visitReturnInst(ReturnInst &RI) {
Value *RetVal = RI.getReturnValue();
- if (!RetVal || !AttributeFuncs::isNoFPClassCompatibleType(RetVal->getType()))
+ if (!RetVal)
+ return nullptr;
+
+ if (RetVal->getType()->isPointerTy() && RI.getFunction()->isReturnNonNull()) {
+ if (Value *V = simplifyNonNullOperand(RetVal))
+ return replaceOperand(RI, 0, V);
+ }
+
+ if (!AttributeFuncs::isNoFPClassCompatibleType(RetVal->getType()))
return nullptr;
Function *F = RI.getFunction();
diff --git a/llvm/test/Transforms/InstCombine/nonnull-select.ll b/llvm/test/Transforms/InstCombine/nonnull-select.ll
index 3fab2dfb41a42..cc000b4c88164 100644
--- a/llvm/test/Transforms/InstCombine/nonnull-select.ll
+++ b/llvm/test/Transforms/InstCombine/nonnull-select.ll
@@ -5,10 +5,7 @@
define nonnull ptr @pr48975(ptr %.0) {
; CHECK-LABEL: @pr48975(
-; CHECK-NEXT: [[DOT1:%.*]] = load ptr, ptr [[DOT0:%.*]], align 8
-; CHECK-NEXT: [[DOT2:%.*]] = icmp eq ptr [[DOT1]], null
-; CHECK-NEXT: [[DOT4:%.*]] = select i1 [[DOT2]], ptr null, ptr [[DOT0]]
-; CHECK-NEXT: ret ptr [[DOT4]]
+; CHECK-NEXT: ret ptr [[DOT4:%.*]]
;
%.1 = load ptr, ptr %.0, align 8
%.2 = icmp eq ptr %.1, null
@@ -18,8 +15,7 @@ define nonnull ptr @pr48975(ptr %.0) {
define nonnull ptr @nonnull_ret(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_ret(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr [[P:%.*]], ptr null
-; CHECK-NEXT: ret ptr [[RES]]
+; CHECK-NEXT: ret ptr [[RES:%.*]]
;
%res = select i1 %cond, ptr %p, ptr null
ret ptr %res
@@ -27,8 +23,7 @@ define nonnull ptr @nonnull_ret(i1 %cond, ptr %p) {
define nonnull ptr @nonnull_ret2(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_ret2(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr null, ptr [[P:%.*]]
-; CHECK-NEXT: ret ptr [[RES]]
+; CHECK-NEXT: ret ptr [[RES:%.*]]
;
%res = select i1 %cond, ptr null, ptr %p
ret ptr %res
@@ -36,8 +31,7 @@ define nonnull ptr @nonnull_ret2(i1 %cond, ptr %p) {
define nonnull noundef ptr @nonnull_noundef_ret(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_noundef_ret(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr [[P:%.*]], ptr null
-; CHECK-NEXT: ret ptr [[RES]]
+; CHECK-NEXT: ret ptr [[RES:%.*]]
;
%res = select i1 %cond, ptr %p, ptr null
ret ptr %res
@@ -45,8 +39,7 @@ define nonnull noundef ptr @nonnull_noundef_ret(i1 %cond, ptr %p) {
define nonnull noundef ptr @nonnull_noundef_ret2(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_noundef_ret2(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr null, ptr [[P:%.*]]
-; CHECK-NEXT: ret ptr [[RES]]
+; CHECK-NEXT: ret ptr [[RES:%.*]]
;
%res = select i1 %cond, ptr null, ptr %p
ret ptr %res
@@ -55,8 +48,7 @@ define nonnull noundef ptr @nonnull_noundef_ret2(i1 %cond, ptr %p) {
define void @nonnull_call(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_call(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr [[P:%.*]], ptr null
-; CHECK-NEXT: call void @f(ptr nonnull [[RES]])
+; CHECK-NEXT: call void @f(ptr nonnull [[RES:%.*]])
; CHECK-NEXT: ret void
;
%res = select i1 %cond, ptr %p, ptr null
@@ -66,8 +58,7 @@ define void @nonnull_call(i1 %cond, ptr %p) {
define void @nonnull_call2(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_call2(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr null, ptr [[P:%.*]]
-; CHECK-NEXT: call void @f(ptr nonnull [[RES]])
+; CHECK-NEXT: call void @f(ptr nonnull [[RES:%.*]])
; CHECK-NEXT: ret void
;
%res = select i1 %cond, ptr null, ptr %p
@@ -77,8 +68,7 @@ define void @nonnull_call2(i1 %cond, ptr %p) {
define void @nonnull_noundef_call(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_noundef_call(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr [[P:%.*]], ptr null
-; CHECK-NEXT: call void @f(ptr noundef nonnull [[RES]])
+; CHECK-NEXT: call void @f(ptr noundef nonnull [[RES:%.*]])
; CHECK-NEXT: ret void
;
%res = select i1 %cond, ptr %p, ptr null
@@ -88,8 +78,7 @@ define void @nonnull_noundef_call(i1 %cond, ptr %p) {
define void @nonnull_noundef_call2(i1 %cond, ptr %p) {
; CHECK-LABEL: @nonnull_noundef_call2(
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND:%.*]], ptr null, ptr [[P:%.*]]
-; CHECK-NEXT: call void @f(ptr noundef nonnull [[RES]])
+; CHECK-NEXT: call void @f(ptr noundef nonnull [[RES:%.*]])
; CHECK-NEXT: ret void
;
%res = select i1 %cond, ptr null, ptr %p
diff --git a/llvm/test/Transforms/PhaseOrdering/load-store-sameval.ll b/llvm/test/Transforms/PhaseOrdering/load-store-sameval.ll
index d8ef0723cf09e..f6bf57a678786 100644
--- a/llvm/test/Transforms/PhaseOrdering/load-store-sameval.ll
+++ b/llvm/test/Transforms/PhaseOrdering/load-store-sameval.ll
@@ -1,24 +1,21 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -passes='instcombine,early-cse<memssa>' -S %s | FileCheck %s
-; FIXME: We can remove the store instruction in the exit block
define i32 @load_store_sameval(ptr %p, i1 %cond1, i1 %cond2) {
; CHECK-LABEL: define i32 @load_store_sameval(
; CHECK-SAME: ptr [[P:%.*]], i1 [[COND1:%.*]], i1 [[COND2:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
-; CHECK-NEXT: [[SPEC_SELECT:%.*]] = select i1 [[COND1]], ptr null, ptr [[P]]
-; CHECK-NEXT: [[PRE:%.*]] = load i32, ptr [[SPEC_SELECT]], align 4
+; CHECK-NEXT: [[PRE:%.*]] = load i32, ptr [[P]], align 4
; CHECK-NEXT: br label %[[BLOCK:.*]]
; CHECK: [[BLOCK]]:
; CHECK-NEXT: br label %[[BLOCK2:.*]]
; CHECK: [[BLOCK2]]:
; CHECK-NEXT: br i1 [[COND2]], label %[[BLOCK3:.*]], label %[[EXIT:.*]]
; CHECK: [[BLOCK3]]:
-; CHECK-NEXT: [[LOAD:%.*]] = load double, ptr [[SPEC_SELECT]], align 8
+; CHECK-NEXT: [[LOAD:%.*]] = load double, ptr [[P]], align 8
; CHECK-NEXT: [[CMP:%.*]] = fcmp une double [[LOAD]], 0.000000e+00
; CHECK-NEXT: br i1 [[CMP]], label %[[BLOCK]], label %[[BLOCK2]]
; CHECK: [[EXIT]]:
-; CHECK-NEXT: store i32 [[PRE]], ptr [[P]], align 4
; CHECK-NEXT: ret i32 0
;
entry:
diff --git a/llvm/test/Transforms/PhaseOrdering/memset-combine.ll b/llvm/test/Transforms/PhaseOrdering/memset-combine.ll
new file mode 100644
index 0000000000000..d1de11258ed91
--- /dev/null
+++ b/llvm/test/Transforms/PhaseOrdering/memset-combine.ll
@@ -0,0 +1,20 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+
+; RUN: opt < %s -passes=instcombine,memcpyopt -S | FileCheck %s
+
+; FIXME: These two memset calls should be merged into a single one.
+define void @merge_memset(ptr %p, i1 %cond) {
+; CHECK-LABEL: define void @merge_memset(
+; CHECK-SAME: ptr [[P:%.*]], i1 [[COND:%.*]]) {
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[COND]], ptr null, ptr [[P]]
+; CHECK-NEXT: tail call void @llvm.memset.p0.i64(ptr noundef nonnull align 1 dereferenceable(4096) [[P]], i8 0, i64 4096, i1 false)
+; CHECK-NEXT: [[OFF:%.*]] = getelementptr inbounds nuw i8, ptr [[SEL]], i64 4096
+; CHECK-NEXT: tail call void @llvm.memset.p0.i64(ptr noundef nonnull align 1 dereferenceable(768) [[OFF]], i8 0, i64 768, i1 false)
+; CHECK-NEXT: ret void
+;
+ %sel = select i1 %cond, ptr null, ptr %p
+ tail call void @llvm.memset.p0.i64(ptr noundef nonnull %sel, i8 0, i64 4096, i1 false)
+ %off = getelementptr inbounds nuw i8, ptr %sel, i64 4096
+ tail call void @llvm.memset.p0.i64(ptr noundef nonnull %off, i8 0, i64 768, i1 false)
+ ret void
+}
|
This was referenced Feb 21, 2025
|
https://llvm-compile-time-tracker.com/compare.php?from=70dfcf83a6bf580e0df50cc6c50d4ba1f9c5250a&to=57a65fa59634d5a0e207063675ed47ecfe47d44c&stat=instructions:u => Interesting results, looks like this has a major positive impact on clang. |
nikic
reviewed
Feb 21, 2025
| replaceOperand(Call, ArgNo, Res); | ||
| Changed = true; | ||
| } | ||
| } |
There was a problem hiding this comment.
Can else this instead of querying nonnull again? (Will no longer infer nonnull for dereferenceable, but we shouldn't need to ?)
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This patch is the follow-up of #127979. It introduces a helper
simplifyNonNullOperandto avoid duplicate logic. It also addresses the one-use issue invisitLoadInst, as discussed in #127979 (comment).The
nonnullattribute is also supported. Proof: https://alive2.llvm.org/ce/z/MCKgT9Based on #128107.