Remove dead instructions before Redoing

Before reevaluating instructions, iterate over all instructions
to be reevaluated and remove trivially dead instructions and if
any of it's operands become trivially dead, mark it for deletion
until all trivially dead instructions have been removed

llvm-svn: 256773

2 files changed, 35 insertions, 1 deletions

diff --git a/llvm/test/Transforms/Reassociate/factorize-again.ll b/llvm/test/Transforms/Reassociate/factorize-again.ll
new file mode 100644
index 00000000000..87e77945dfb
--- /dev/null
+++ b/llvm/test/Transforms/Reassociate/factorize-again.ll
@@ -0,0 +1,34 @@
+; RUN: opt -S -reassociate < %s | FileCheck %s
+
+; CHECK-LABEL: main
+; CHECK: %2 = fsub
+; CHECK: %3 = fsub
+; CHECK: fadd fast float %3, %2
+define void @main(float, float) {
+wrapper_entry:
+  %2 = fsub float undef, %0
+  %3 = fsub float undef, %1
+  %4 = call float @llvm.rsqrt.f32(float undef)
+  %5 = fmul fast float undef, %4
+  %6 = fmul fast float %2, %4
+  %7 = fmul fast float %3, %4
+  %8 = fmul fast float %5, undef
+  %9 = fmul fast float %6, undef
+  %10 = fmul fast float %7, undef
+  %11 = fadd fast float %8, %9
+  %12 = fadd fast float %11, %10
+  %13 = call float @foo2(float %12, float 0.000000e+00)
+  %mul36 = fmul fast float %13, 1.500000e+00
+  call void @foo1(i32 4, float %mul36)
+  ret void
+}
+
+declare void @foo1(i32, float)
+
+declare float @foo2(float, float) #1
+
+declare float @llvm.rsqrt.f32(float) #1
+
+attributes #0 = { argmemonly nounwind }
+attributes #1 = { nounwind readnone }
+
diff --git a/llvm/test/Transforms/Reassociate/secondary.ll b/llvm/test/Transforms/Reassociate/secondary.ll
index 388cd6bcb6f..a52000ada53 100644
--- a/llvm/test/Transforms/Reassociate/secondary.ll
+++ b/llvm/test/Transforms/Reassociate/secondary.ll
@@ -6,7 +6,7 @@
 
 ; CHECK:     define
 ; CHECK-NOT: undef
-; CHECK:     %factor = mul i32 %tmp3.neg, 2
+; CHECK:     %factor = mul i32 %tmp3, -2
 ; CHECK-NOT: undef
 ; CHECK:     }