[CodeGen] Use CreateFNeg in buildFMulAdd

We have an fneg instruction now and should use it instead of the fsub -0.0 idiom. Looks like we had no test that showed that we handled the negation cases here so I've added new tests.

Differential Revision: https://reviews.llvm.org/D72010

1 files changed, 15 insertions, 0 deletions

diff --git a/clang/test/CodeGen/fp-contract-pragma.cpp b/clang/test/CodeGen/fp-contract-pragma.cpp
index 1c5921a53f9..805cc5d9c29 100644
--- a/clang/test/CodeGen/fp-contract-pragma.cpp
+++ b/clang/test/CodeGen/fp-contract-pragma.cpp
@@ -74,3 +74,18 @@ float fp_contract_7(float a, float b, float c) {
   return (a = 2 * b) - c;
 }
 
+float fp_contract_8(float a, float b, float c) {
+// CHECK: _Z13fp_contract_8fff
+// CHECK: fneg float %c
+// CHECK: tail call float @llvm.fmuladd
+  #pragma STDC FP_CONTRACT ON
+  return a * b - c;
+}
+
+float fp_contract_9(float a, float b, float c) {
+// CHECK: _Z13fp_contract_9fff
+// CHECK: fneg float %a
+// CHECK: tail call float @llvm.fmuladd
+  #pragma STDC FP_CONTRACT ON
+  return c - a * b;
+}