llvm-6502/test/Transforms/InstCombine/fabs.ll
Sanjay Patel 3f349b2ba8 Optimize away fabs() calls when input is squared (known positive).
Eliminate library calls and intrinsic calls to fabs when the input 
is a squared value.

Note that no unsafe-math / fast-math assumptions are needed for
this optimization.

Differential Revision: http://reviews.llvm.org/D5777



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219717 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-14 20:43:11 +00:00

101 lines
2.7 KiB
LLVM

; RUN: opt < %s -instcombine -S | FileCheck %s
; Make sure all library calls are eliminated when the input is known positive.
declare float @fabsf(float)
declare double @fabs(double)
declare fp128 @fabsl(fp128)
define float @square_fabs_call_f32(float %x) {
%mul = fmul float %x, %x
%fabsf = tail call float @fabsf(float %mul)
ret float %fabsf
; CHECK-LABEL: square_fabs_call_f32(
; CHECK-NEXT: %mul = fmul float %x, %x
; CHECK-NEXT: ret float %mul
}
define double @square_fabs_call_f64(double %x) {
%mul = fmul double %x, %x
%fabs = tail call double @fabs(double %mul)
ret double %fabs
; CHECK-LABEL: square_fabs_call_f64(
; CHECK-NEXT: %mul = fmul double %x, %x
; CHECK-NEXT: ret double %mul
}
define fp128 @square_fabs_call_f128(fp128 %x) {
%mul = fmul fp128 %x, %x
%fabsl = tail call fp128 @fabsl(fp128 %mul)
ret fp128 %fabsl
; CHECK-LABEL: square_fabs_call_f128(
; CHECK-NEXT: %mul = fmul fp128 %x, %x
; CHECK-NEXT: ret fp128 %mul
}
; Make sure all intrinsic calls are eliminated when the input is known positive.
declare float @llvm.fabs.f32(float)
declare double @llvm.fabs.f64(double)
declare fp128 @llvm.fabs.f128(fp128)
define float @square_fabs_intrinsic_f32(float %x) {
%mul = fmul float %x, %x
%fabsf = tail call float @llvm.fabs.f32(float %mul)
ret float %fabsf
; CHECK-LABEL: square_fabs_intrinsic_f32(
; CHECK-NEXT: %mul = fmul float %x, %x
; CHECK-NEXT: ret float %mul
}
define double @square_fabs_intrinsic_f64(double %x) {
%mul = fmul double %x, %x
%fabs = tail call double @llvm.fabs.f64(double %mul)
ret double %fabs
; CHECK-LABEL: square_fabs_intrinsic_f64(
; CHECK-NEXT: %mul = fmul double %x, %x
; CHECK-NEXT: ret double %mul
}
define fp128 @square_fabs_intrinsic_f128(fp128 %x) {
%mul = fmul fp128 %x, %x
%fabsl = tail call fp128 @llvm.fabs.f128(fp128 %mul)
ret fp128 %fabsl
; CHECK-LABEL: square_fabs_intrinsic_f128(
; CHECK-NEXT: %mul = fmul fp128 %x, %x
; CHECK-NEXT: ret fp128 %mul
}
; Shrinking a library call to a smaller type should not be inhibited by nor inhibit the square optimization.
define float @square_fabs_shrink_call1(float %x) {
%ext = fpext float %x to double
%sq = fmul double %ext, %ext
%fabs = call double @fabs(double %sq)
%trunc = fptrunc double %fabs to float
ret float %trunc
; CHECK-LABEL: square_fabs_shrink_call1(
; CHECK-NEXT: %trunc = fmul float %x, %x
; CHECK-NEXT: ret float %trunc
}
define float @square_fabs_shrink_call2(float %x) {
%sq = fmul float %x, %x
%ext = fpext float %sq to double
%fabs = call double @fabs(double %ext)
%trunc = fptrunc double %fabs to float
ret float %trunc
; CHECK-LABEL: square_fabs_shrink_call2(
; CHECK-NEXT: %sq = fmul float %x, %x
; CHECK-NEXT: ret float %sq
}