Fix an issue where fast math flags were dropped during scalarization.

Most portions of InstCombine properly propagate fast math flags, but
apparently the vector scalarization section was overlooked.

llvm-svn: 262376

1 files changed, 39 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/fast-math-scalarization.ll b/llvm/test/Transforms/InstCombine/fast-math-scalarization.ll
new file mode 100644
index 00000000000..406ebebfdd2
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/fast-math-scalarization.ll
@@ -0,0 +1,39 @@
+; RUN: opt -instcombine -S < %s | FileCheck %s
+
+; CHECK-LABEL: test_scalarize_phi
+; CHECK: fmul fast float
+define void @test_scalarize_phi(i32 * %n, float * %inout) {
+entry:
+  %0 = load volatile float, float * %inout, align 4
+  %splat.splatinsert = insertelement <4 x float> undef, float %0, i32 0
+  %splat.splat = shufflevector <4 x float> %splat.splatinsert, <4 x float> undef, <4 x i32> zeroinitializer
+  %splat.splatinsert1 = insertelement <4 x float> undef, float 3.0, i32 0
+  br label %for.cond
+
+for.cond:
+  %x.0 = phi <4 x float> [ %splat.splat, %entry ], [ %mul, %for.body ]
+  %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %1 = load i32, i32 * %n, align 4
+  %cmp = icmp ne i32 %i.0, %1
+  br i1 %cmp, label %for.body, label %for.end
+
+for.body:
+  %2 = extractelement <4 x float> %x.0, i32 1
+  store volatile float %2, float * %inout, align 4
+  %mul = fmul fast <4 x float> %x.0, <float 0x4002A3D700000000, float 0x4002A3D700000000, float 0x4002A3D700000000, float 0x4002A3D700000000>
+  %inc = add nsw i32 %i.0, 1
+  br label %for.cond
+
+for.end:
+  ret void
+}
+
+; CHECK-LABEL: test_extract_element_fastmath
+; CHECK: fadd fast float
+define float @test_extract_element_fastmath(<4 x float> %x) #0 {
+entry:
+  %add = fadd fast <4 x float> %x, <float 0x4002A3D700000000, float 0x4002A3D700000000, float 0x4002A3D700000000, float 0x4002A3D700000000>
+  %0 = extractelement <4 x float> %add, i32 2
+  ret float %0
+}
+