Add FP_CONTRACT support for clang.

Clang will now honor the FP_CONTRACT pragma and emit LLVM
fmuladd intrinsics for expressions of the form A * B + C (when they occur in a
single statement).

llvm-svn: 164989

1 files changed, 39 insertions, 0 deletions

diff --git a/clang/test/CodeGen/fp-contract-pragma.cpp b/clang/test/CodeGen/fp-contract-pragma.cpp
new file mode 100644
index 00000000000..8c51469c473
--- /dev/null
+++ b/clang/test/CodeGen/fp-contract-pragma.cpp
@@ -0,0 +1,39 @@
+// RUN: %clang_cc1 -O3 -emit-llvm -o - %s | FileCheck %s
+
+// Is FP_CONTRACT is honored in a simple case?
+float fp_contract_1(float a, float b, float c) {
+// CHECK: _Z13fp_contract_1fff
+// CHECK-NEXT: entry
+// CHECK-NEXT: %0 = tail call float @llvm.fmuladd
+  #pragma STDC FP_CONTRACT ON
+  return a * b + c;
+}
+
+// Is FP_CONTRACT state cleared on exiting compound statements?
+float fp_contract_2(float a, float b, float c) {
+// CHECK: _Z13fp_contract_2fff
+// CHECK-NEXT: entry
+// CHECK-NEXT: %mul = fmul float %a, %b
+// CHECK-NEXT: %add = fadd float %mul, %c
+  {
+    #pragma STDC FP_CONTRACT ON
+  }
+  return a * b + c;  
+}
+
+// Does FP_CONTRACT survive template instatiation?
+class Foo {};
+Foo operator+(Foo, Foo);
+
+template <typename T>
+T template_muladd(T a, T b, T c) {
+  #pragma STDC FP_CONTRACT ON
+  return a * b + c;
+}
+
+float fp_contract_3(float a, float b, float c) {
+// CHECK: _Z13fp_contract_3fff
+// CHECK-NEXT: entry
+// CHECK-NEXT: %0 = tail call float @llvm.fmuladd
+  return template_muladd<float>(a, b, c);
+}