Added fix to enable constant folding that is missing for math library functions (scalbln , scalbn, ldexp) #169893
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@llvm/pr-subscribers-llvm-transforms Author: Raja Sudha Sri Harika (Sriharika1506) ChangesIssue : #112631 This patch adds support for constant folding for certain math library functions wherever it was previously missing. Full diff: https://github.com/llvm/llvm-project/pull/169893.diff 2 Files Affected:
diff --git a/llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h b/llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h
index 4e7c97194cc59..72b8f4b427b3b 100644
--- a/llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h
+++ b/llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h
@@ -214,6 +214,9 @@ class LibCallSimplifier {
Value *optimizeSymmetric(CallInst *CI, LibFunc Func, IRBuilderBase &B);
Value *optimizeRemquo(CallInst *CI, IRBuilderBase &B);
Value *optimizeFdim(CallInst *CI, IRBuilderBase &B);
+
+ Value *foldLdexp(CallInst *CI, IRBuilderBase &B);
+
// Wrapper for all floating point library call optimizations
Value *optimizeFloatingPointLibCall(CallInst *CI, LibFunc Func,
IRBuilderBase &B);
diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 4a1565977b91c..7508048d3032e 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -2464,6 +2464,24 @@ Value *LibCallSimplifier::optimizePow(CallInst *Pow, IRBuilderBase &B) {
return nullptr;
}
+Value *LibCallSimplifier::foldLdexp(CallInst *CI,IRBuilderBase &B) {
+
+ Type*RequiredType = CI->getType();
+ if(!RequiredType->isFPOrFPVectorTy())
+ return nullptr;
+
+ Value*x = CI->getArgOperand(0);
+ Value*exp = CI->getArgOperand(1);
+ Module*M = CI->getModule();
+
+ Function*ldexpDecl = llvm::Intrinsic::getOrInsertDeclaration(M, Intrinsic::ldexp,{RequiredType, exp->getType()});
+
+ CallInst *NewCall = B.CreateCall(ldexpDecl, {x, exp}, CI->getName());
+ NewCall->setAttributes(CI->getAttributes());
+ return copyFlags(*CI, NewCall);
+}
+
+
Value *LibCallSimplifier::optimizeExp2(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
Function *Callee = CI->getCalledFunction();
@@ -4031,6 +4049,17 @@ Value *LibCallSimplifier::optimizeFloatingPointLibCall(CallInst *CI,
case LibFunc_exp2:
case LibFunc_exp2f:
return optimizeExp2(CI, Builder);
+ // New ldexp / scalbn / scalbln family:
+ case LibFunc_ldexp:
+ case LibFunc_ldexpf:
+ case LibFunc_ldexpl:
+ case LibFunc_scalbn:
+ case LibFunc_scalbnf:
+ case LibFunc_scalbnl:
+ case LibFunc_scalbln:
+ case LibFunc_scalblnf:
+ case LibFunc_scalblnl:
+ return foldLdexp(CI, Builder);
case LibFunc_fabsf:
case LibFunc_fabs:
case LibFunc_fabsl:
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Author
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@ashwinagrl @YogeshFebyani also worked on this |
Author
Contributor
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Consider referencing PR #114417 and adding corresponding tests |
You can test this locally with the following command:git-clang-format --diff origin/main HEAD --extensions h,cpp -- llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp --diff_from_common_commit
View the diff from clang-format here.diff --git a/llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h b/llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h
index 72b8f4b42..67d6bb133 100644
--- a/llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h
+++ b/llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h
@@ -216,7 +216,7 @@ private:
Value *optimizeFdim(CallInst *CI, IRBuilderBase &B);
Value *foldLdexp(CallInst *CI, IRBuilderBase &B);
-
+
// Wrapper for all floating point library call optimizations
Value *optimizeFloatingPointLibCall(CallInst *CI, LibFunc Func,
IRBuilderBase &B);
diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 702705ec0..809af8d3f 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -2469,24 +2469,24 @@ Value *LibCallSimplifier::optimizePow(CallInst *Pow, IRBuilderBase &B) {
return nullptr;
}
-Value *LibCallSimplifier::foldLdexp(CallInst *CI,IRBuilderBase &B) {
+Value *LibCallSimplifier::foldLdexp(CallInst *CI, IRBuilderBase &B) {
- Type*RequiredType = CI->getType();
- if(!RequiredType->isFPOrFPVectorTy())
+ Type *RequiredType = CI->getType();
+ if (!RequiredType->isFPOrFPVectorTy())
return nullptr;
- Value*x = CI->getArgOperand(0);
- Value*exp = CI->getArgOperand(1);
- Module*M = CI->getModule();
+ Value *x = CI->getArgOperand(0);
+ Value *exp = CI->getArgOperand(1);
+ Module *M = CI->getModule();
+
+ Function *ldexpDecl = llvm::Intrinsic::getOrInsertDeclaration(
+ M, Intrinsic::ldexp, {RequiredType, exp->getType()});
- Function*ldexpDecl = llvm::Intrinsic::getOrInsertDeclaration(M, Intrinsic::ldexp,{RequiredType, exp->getType()});
-
CallInst *NewCall = B.CreateCall(ldexpDecl, {x, exp}, CI->getName());
NewCall->setAttributes(CI->getAttributes());
return copyFlags(*CI, NewCall);
}
-
Value *LibCallSimplifier::optimizeExp2(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
Function *Callee = CI->getCalledFunction();
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dtcxzyw
requested changes
Nov 28, 2025
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dtcxzyw
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dtcxzyw
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I'd suggest modifying the code based on https://github.com/llvm/llvm-project/pull/114417/files and fixing previous comments.
I am a bit confused that you are fixing an issue that was assigned to @ashwinagrl. Have you two communicated with each other?
Author
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@dtcxzyw We are working in a team along with @ashwinagrl. |
🐧 Linux x64 Test Results
Failed Tests(click on a test name to see its output) LLVMLLVM.Transforms/InstCombine/RISCV/libcall-arg-exts.llLLVM.Transforms/InstCombine/SystemZ/libcall-arg-exts.llLLVM.Transforms/InstCombine/exp2-1.llLLVM.Transforms/InstCombine/pow-to-ldexp.llLLVM.Transforms/InstCombine/simplify-libcalls-i16.llLLVM.Transforms/InstCombine/simplify-libcalls.llIf these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the |
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Issue : #112631
This patch adds support for constant folding for certain math library functions wherever it was previously missing.