llvm/test/Transforms/InstCombine/phi-preserve-ir-flags.ll
Silviu Baranga 883a09c5a6 [InstCombine] Preserve fast math flags when combining PHIs
Summary:
When optimizing PHIs which have inputs floating point binary
operators, we preserve all IR flags except the fast math
flags.

This change removes the logic which tracked some of the IR flags
(no wrap, exact) and replaces it by doing an and on the IR flags of
all inputs to the PHI - which will also handle the fast math
flags.

Reviewers: majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D19370

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267139 91177308-0d34-0410-b5e6-96231b3b80d8
2016-04-22 11:21:36 +00:00

90 lines
2.3 KiB
LLVM

; RUN: opt < %s -instcombine -S -o - | FileCheck %s
target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
; CHECK-LABEL: define float @func1(
define float @func1(float %a, float %b, float %c, i1 %cond) {
entry:
br i1 %cond, label %cond.true, label %cond.false
cond.true:
%sub0 = fsub fast float %a, %b
br label %cond.end
cond.false:
%sub1 = fsub fast float %a, %c
br label %cond.end
; The fast-math flags should always be transfered if possible.
; CHECK-LABEL: cond.end
; CHECK [[PHI:%[^ ]*]] = phi float [ %b, %cond.true ], [ %c, %cond.false ]
; CHECK fsub fast float %a, [[PHI]]
cond.end:
%e = phi float [ %sub0, %cond.true ], [ %sub1, %cond.false ]
ret float %e
}
; CHECK-LABEL: define float @func2(
define float @func2(float %a, float %b, float %c, i1 %cond) {
entry:
br i1 %cond, label %cond.true, label %cond.false
cond.true:
%sub0 = fsub fast float %a, %b
br label %cond.end
cond.false:
%sub1 = fsub float %a, %c
br label %cond.end
; The fast-math flags should always be transfered if possible.
; CHECK-LABEL: cond.end
; CHECK [[PHI:%[^ ]*]] = phi float [ %b, %cond.true ], [ %c, %cond.false ]
; CHECK fsub float %a, [[PHI]]
cond.end:
%e = phi float [ %sub0, %cond.true ], [ %sub1, %cond.false ]
ret float %e
}
; CHECK-LABEL: define float @func3(
define float @func3(float %a, float %b, float %c, i1 %cond) {
entry:
br i1 %cond, label %cond.true, label %cond.false
cond.true:
%sub0 = fsub fast float %a, 2.0
br label %cond.end
cond.false:
%sub1 = fsub fast float %b, 2.0
br label %cond.end
; CHECK-LABEL: cond.end
; CHECK [[PHI:%[^ ]*]] = phi float [ %a, %cond.true ], [ %b, %cond.false ]
; CHECK fadd fast float %a, [[PHI]]
cond.end:
%e = phi float [ %sub0, %cond.true ], [ %sub1, %cond.false ]
ret float %e
}
; CHECK-LABEL: define float @func4(
define float @func4(float %a, float %b, float %c, i1 %cond) {
entry:
br i1 %cond, label %cond.true, label %cond.false
cond.true:
%sub0 = fsub fast float %a, 2.0
br label %cond.end
cond.false:
%sub1 = fsub float %b, 2.0
br label %cond.end
; CHECK-LABEL: cond.end
; CHECK [[PHI:%[^ ]*]] = phi float [ %a, %cond.true ], [ %b, %cond.false ]
; CHECK fadd float %a, [[PHI]]
cond.end:
%e = phi float [ %sub0, %cond.true ], [ %sub1, %cond.false ]
ret float %e
}