Fold FP comparisons where one operand is converted from an integer

type and the other operand is a constant into integer comparisons.
This happens surprisingly frequently (e.g. 10 times in 471.omnetpp),
which are things like this:

	%tmp8283 = sitofp i32 %tmp82 to double	
	%tmp1013 = fcmp ult double %tmp8283, 0.0

Clearly comparing tmp82 against i32 0 is cheaper here.

this also triggers 8 times in gobmk, including this one:

	%tmp375376 = sitofp i32 %tmp375 to double
	%tmp377 = fcmp ogt double %tmp375376, 8.150000e+01

which is comparing an integer against 81.5 :).



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51268 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 25 insertions, 0 deletions

diff --git a/test/Transforms/InstCombine/sitofp.ll b/test/Transforms/InstCombine/sitofp.ll
new file mode 100644
index 0000000..fd06dea
--- /dev/null
+++ b/test/Transforms/InstCombine/sitofp.ll
@@ -0,0 +1,25 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep sitofp
+
+define i1 @test1(i8 %A) {
+  %B = sitofp i8 %A to double
+  %C = fcmp ult double %B, 128.0
+  ret i1 %C  ;  True!
+}
+define i1 @test2(i8 %A) {
+  %B = sitofp i8 %A to double
+  %C = fcmp ugt double %B, -128.1
+  ret i1 %C  ;  True!
+}
+
+define i1 @test3(i8 %A) {
+  %B = sitofp i8 %A to double
+  %C = fcmp ule double %B, 127.0
+  ret i1 %C  ;  true!
+}
+
+define i1 @test4(i8 %A) {
+  %B = sitofp i8 %A to double
+  %C = fcmp ult double %B, 127.0
+  ret i1 %C  ;  A != 127
+}
+