Instruction::isAssociative() returns true for fmul/fadd if they are tagged "unsafe" mode.

Approved by: Eli and Michael.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168848 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 32 insertions, 0 deletions

diff --git a/test/Transforms/InstCombine/fast-math.ll b/test/Transforms/InstCombine/fast-math.ll
new file mode 100644
index 0000000000..42241409ff
--- /dev/null
+++ b/test/Transforms/InstCombine/fast-math.ll
@@ -0,0 +1,32 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; testing-case "float fold(float a) { return 1.2f * a * 2.3f; }"
+; 1.2f and 2.3f is supposed to be fold.
+define float @fold(float %a) {
+fold:
+  %mul = fmul fast float %a, 0x3FF3333340000000
+  %mul1 = fmul fast float %mul, 0x4002666660000000
+  ret float %mul1
+; CHECK: fold
+; CHECK: fmul float %a, 0x4006147AE0000000
+}
+
+; Same testing-case as the one used in fold() except that the operators have
+; fixed FP mode.
+define float @notfold(float %a) {
+notfold:
+; CHECK: notfold
+; CHECK: %mul = fmul fast float %a, 0x3FF3333340000000
+  %mul = fmul fast float %a, 0x3FF3333340000000
+  %mul1 = fmul float %mul, 0x4002666660000000
+  ret float %mul1
+}
+
+define float @fold2(float %a) {
+notfold2:
+; CHECK: fold2
+; CHECK: fmul float %a, 0x4006147AE0000000
+  %mul = fmul float %a, 0x3FF3333340000000
+  %mul1 = fmul fast float %mul, 0x4002666660000000
+  ret float %mul1
+}