Merge pull request #783 from rust-lang/fix/ram-usage

Fix RAM usage by splitting deeply nested expressions

Author: antoyo

src/builder.rs

@@ -668,32 +668,38 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
     }
 
     fn add(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        self.gcc_add(a, b)
+        self.assign_to_var(self.gcc_add(a, b))
     }
 
     fn fadd(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        a + b
+        self.assign_to_var(a + b)
     }
 
     // TODO(antoyo): should we also override the `unchecked_` versions?
     fn sub(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        self.gcc_sub(a, b)
+        self.assign_to_var(self.gcc_sub(a, b))
     }
 
     fn fsub(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        a - b
+        self.assign_to_var(a - b)
     }
 
     fn mul(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        self.gcc_mul(a, b)
+        self.assign_to_var(self.gcc_mul(a, b))
     }
 
     fn fmul(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        self.cx.context.new_binary_op(self.location, BinaryOp::Mult, a.get_type(), a, b)
+        self.assign_to_var(self.cx.context.new_binary_op(
+            self.location,
+            BinaryOp::Mult,
+            a.get_type(),
+            a,
+            b,
+        ))
     }
 
     fn udiv(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        self.gcc_udiv(a, b)
+        self.assign_to_var(self.gcc_udiv(a, b))
     }
 
     fn exactudiv(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
@@ -702,11 +708,11 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         let a = self.gcc_int_cast(a, a_type);
         let b_type = b.get_type().to_unsigned(self);
         let b = self.gcc_int_cast(b, b_type);
-        self.gcc_udiv(a, b)
+        self.assign_to_var(self.gcc_udiv(a, b))
     }
 
     fn sdiv(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        self.gcc_sdiv(a, b)
+        self.assign_to_var(self.gcc_sdiv(a, b))
     }
 
     fn exactsdiv(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
@@ -715,19 +721,19 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         // should be the same.
         let typ = a.get_type().to_signed(self);
         let b = self.gcc_int_cast(b, typ);
-        self.gcc_sdiv(a, b)
+        self.assign_to_var(self.gcc_sdiv(a, b))
     }
 
     fn fdiv(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        a / b
+        self.assign_to_var(a / b)
     }
 
     fn urem(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        self.gcc_urem(a, b)
+        self.assign_to_var(self.gcc_urem(a, b))
     }
 
     fn srem(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        self.gcc_srem(a, b)
+        self.assign_to_var(self.gcc_srem(a, b))
     }
 
     fn frem(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
@@ -865,22 +871,26 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
 
     fn fadd_fast(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>) -> RValue<'gcc> {
         // NOTE: it seems like we cannot enable fast-mode for a single operation in GCC.
-        set_rvalue_location(self, lhs + rhs)
+        let result = set_rvalue_location(self, lhs + rhs);
+        self.assign_to_var(result)
     }
 
     fn fsub_fast(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>) -> RValue<'gcc> {
         // NOTE: it seems like we cannot enable fast-mode for a single operation in GCC.
-        set_rvalue_location(self, lhs - rhs)
+        let result = set_rvalue_location(self, lhs - rhs);
+        self.assign_to_var(result)
     }
 
     fn fmul_fast(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>) -> RValue<'gcc> {
         // NOTE: it seems like we cannot enable fast-mode for a single operation in GCC.
-        set_rvalue_location(self, lhs * rhs)
+        let result = set_rvalue_location(self, lhs * rhs);
+        self.assign_to_var(result)
     }
 
     fn fdiv_fast(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>) -> RValue<'gcc> {
         // NOTE: it seems like we cannot enable fast-mode for a single operation in GCC.
-        set_rvalue_location(self, lhs / rhs)
+        let result = set_rvalue_location(self, lhs / rhs);
+        self.assign_to_var(result)
     }
 
     fn frem_fast(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>) -> RValue<'gcc> {
@@ -892,22 +902,22 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
 
     fn fadd_algebraic(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>) -> RValue<'gcc> {
         // NOTE: it seems like we cannot enable fast-mode for a single operation in GCC.
-        lhs + rhs
+        self.assign_to_var(lhs + rhs)
     }
 
     fn fsub_algebraic(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>) -> RValue<'gcc> {
         // NOTE: it seems like we cannot enable fast-mode for a single operation in GCC.
-        lhs - rhs
+        self.assign_to_var(lhs - rhs)
     }
 
     fn fmul_algebraic(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>) -> RValue<'gcc> {
         // NOTE: it seems like we cannot enable fast-mode for a single operation in GCC.
-        lhs * rhs
+        self.assign_to_var(lhs * rhs)
     }
 
     fn fdiv_algebraic(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>) -> RValue<'gcc> {
         // NOTE: it seems like we cannot enable fast-mode for a single operation in GCC.
-        lhs / rhs
+        self.assign_to_var(lhs / rhs)
     }
 
     fn frem_algebraic(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>) -> RValue<'gcc> {
@@ -2409,6 +2419,15 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
         let res = then_vals | else_vals;
         self.bitcast_if_needed(res, result_type)
     }
+
+    // GCC doesn't like deeply nested expressions.
+    // By assigning intermediate expressions to a variable, this allow us to avoid deeply nested
+    // expressions and GCC will use much less RAM.
+    fn assign_to_var(&self, value: RValue<'gcc>) -> RValue<'gcc> {
+        let var = self.current_func().new_local(self.location, value.get_type(), "opResult");
+        self.llbb().add_assignment(self.location, var, value);
+        var.to_rvalue()
+    }
 }
 
 fn difference_or_zero<'gcc>(