llvm-6502/test/Transforms/InstSimplify/floating-point-compare.ll
Elena Demikhovsky b5c82c079a Fold fcmp in cases where value is provably non-negative. By Arch Robison.
This patch folds fcmp in some cases of interest in Julia. The patch adds a function CannotBeOrderedLessThanZero that returns true if a value is provably not less than zero. I.e. the function returns true if the value is provably -0, +0, positive, or a NaN. The patch extends InstructionSimplify.cpp to fold instances of fcmp where:
 - the predicate is olt or uge
 - the first operand is provably not less than zero
 - the second operand is zero
The motivation for handling these cases optimizing away domain checks for sqrt in Julia for common idioms such as sqrt(x*x+y*y)..

http://reviews.llvm.org/D6972



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227298 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-28 08:03:58 +00:00

61 lines
1.8 KiB
LLVM

; RUN: opt < %s -instsimplify -S | FileCheck %s
; These tests choose arbitrarily between float and double,
; and between uge and olt, to give reasonble coverage
; without combinatorial explosion.
declare float @llvm.fabs.f32(float)
declare float @llvm.sqrt.f32(float)
declare double @llvm.powi.f64(double,i32)
declare float @llvm.exp.f32(float)
declare double @llvm.exp2.f64(double)
declare float @llvm.fma.f32(float,float,float)
declare void @expect_equal(i1,i1)
; CHECK-LABEL: @orderedLessZeroTree(
define i1 @orderedLessZeroTree(float,float,float,float) {
%square = fmul float %0, %0
%abs = call float @llvm.fabs.f32(float %1)
%sqrt = call float @llvm.sqrt.f32(float %2)
%fma = call float @llvm.fma.f32(float %3, float %3, float %sqrt)
%div = fdiv float %square, %abs
%rem = frem float %sqrt, %fma
%add = fadd float %div, %rem
%uge = fcmp uge float %add, 0.000000e+00
; CHECK: ret i1 true
ret i1 %uge
}
; CHECK-LABEL: @orderedLessZeroExpExt(
define i1 @orderedLessZeroExpExt(float) {
%a = call float @llvm.exp.f32(float %0)
%b = fpext float %a to double
%uge = fcmp uge double %b, 0.000000e+00
; CHECK: ret i1 true
ret i1 %uge
}
; CHECK-LABEL: @orderedLessZeroExp2Trunc(
define i1 @orderedLessZeroExp2Trunc(double) {
%a = call double @llvm.exp2.f64(double %0)
%b = fptrunc double %a to float
%olt = fcmp olt float %b, 0.000000e+00
; CHECK: ret i1 false
ret i1 %olt
}
; CHECK-LABEL: @orderedLessZeroPowi(
define i1 @orderedLessZeroPowi(double,double) {
; Even constant exponent
%a = call double @llvm.powi.f64(double %0, i32 2)
%square = fmul double %1, %1
; Odd constant exponent with provably non-negative base
%b = call double @llvm.powi.f64(double %square, i32 3)
%c = fadd double %a, %b
%olt = fcmp olt double %b, 0.000000e+00
; CHECK: ret i1 false
ret i1 %olt
}