llvm-6502/test/Transforms/InstCombine/fcmp.ll
Jim Grosbach cbf676b3ba float comparison to double 'zero' constant can just be a float 'zero.'
InstCombine was incorrectly considering the conversion of the constant
zero to be unsafe.

We want to transform:
define float @bar(float %x) nounwind readnone optsize ssp {
  %conv = fpext float %x to double
  %cmp = fcmp olt double %conv, 0.000000e+00
  %conv1 = zext i1 %cmp to i32
  %conv2 = sitofp i32 %conv1 to float
  ret float %conv2
}

Into:
define float @bar(float %x) nounwind readnone optsize ssp {
  %cmp = fcmp olt float %x, 0.000000e+00   ; <---- This
  %conv1 = zext i1 %cmp to i32
  %conv2 = sitofp i32 %conv1 to float
  ret float %conv2
}


rdar://10215914


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140869 91177308-0d34-0410-b5e6-96231b3b80d8
2011-09-30 18:45:50 +00:00

72 lines
1.9 KiB
LLVM

; RUN: opt -S -instcombine < %s | FileCheck %s
define i1 @test1(float %x, float %y) nounwind {
%ext1 = fpext float %x to double
%ext2 = fpext float %y to double
%cmp = fcmp ogt double %ext1, %ext2
ret i1 %cmp
; CHECK: @test1
; CHECK-NEXT: fcmp ogt float %x, %y
}
define i1 @test2(float %a) nounwind {
%ext = fpext float %a to double
%cmp = fcmp ogt double %ext, 1.000000e+00
ret i1 %cmp
; CHECK: @test2
; CHECK-NEXT: fcmp ogt float %a, 1.0
}
define i1 @test3(float %a) nounwind {
%ext = fpext float %a to double
%cmp = fcmp ogt double %ext, 0x3FF0000000000001 ; more precision than float.
ret i1 %cmp
; CHECK: @test3
; CHECK-NEXT: fpext float %a to double
}
define i1 @test4(float %a) nounwind {
%ext = fpext float %a to double
%cmp = fcmp ogt double %ext, 0x36A0000000000000 ; denormal in float.
ret i1 %cmp
; CHECK: @test4
; CHECK-NEXT: fpext float %a to double
}
define i1 @test5(float %a) nounwind {
%neg = fsub float -0.000000e+00, %a
%cmp = fcmp ogt float %neg, 1.000000e+00
ret i1 %cmp
; CHECK: @test5
; CHECK-NEXT: fcmp olt float %a, -1.0
}
define i1 @test6(float %x, float %y) nounwind {
%neg1 = fsub float -0.000000e+00, %x
%neg2 = fsub float -0.000000e+00, %y
%cmp = fcmp olt float %neg1, %neg2
ret i1 %cmp
; CHECK: @test6
; CHECK-NEXT: fcmp ogt float %x, %y
}
define i1 @test7(float %x) nounwind readnone ssp noredzone {
%ext = fpext float %x to ppc_fp128
%cmp = fcmp ogt ppc_fp128 %ext, 0xM00000000000000000000000000000000
ret i1 %cmp
; Can't convert ppc_fp128
; CHECK: @test7
; CHECK-NEXT: fpext float %x to ppc_fp128
}
define float @test8(float %x) nounwind readnone optsize ssp {
%conv = fpext float %x to double
%cmp = fcmp olt double %conv, 0.000000e+00
%conv1 = zext i1 %cmp to i32
%conv2 = sitofp i32 %conv1 to float
ret float %conv2
; Float comparison to zero shouldn't cast to double.
; CHECK: @test8
; CHECK-NEXT: fcmp olt float %x, 0.000000e+00
}