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[InstSimplify] Optimize away urems in the presence of range metadata 

We know that urem %V, C can be optimized away to %V if %V is ult C.

llvm-svn: 291282
This commit is contained in:
David Majnemer 2017-01-06 21:23:51 +00:00
parent 27d224fbbb
commit 8c0e62f507
3 changed files with 49 additions and 21 deletions
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10
llvm/lib/Analysis/InstructionSimplify.cpp
View File

@ -1247,6 +1247,16 @@ static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q,
if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse))
return V;
// urem %V, C -> %V if %V < C
if (MaxRecurse) {
if (Constant *C = dyn_cast_or_null<Constant>(SimplifyICmpInst(
ICmpInst::ICMP_ULT, Op0, Op1, Q, MaxRecurse - 1))) {
if (C->isAllOnesValue()) {
return Op0;
}
}
}
return nullptr;
}

46
llvm/test/Transforms/InstCombine/urem-simplify-bug.ll
View File

@ -1,32 +1,36 @@
; RUN: opt < %s -instcombine -S | grep "= or i32 %x, -5"
; RUN: opt < %s -instcombine -S | FileCheck %s
@.str = internal constant [5 x i8] c"foo\0A\00" ; <[5 x i8]*> [#uses=1]
@.str1 = internal constant [5 x i8] c"bar\0A\00" ; <[5 x i8]*> [#uses=1]
@.str = internal constant [5 x i8] c"foo\0A\00"
@.str1 = internal constant [5 x i8] c"bar\0A\00"
define i32 @main() nounwind {
entry:
%x = call i32 @func_11( ) nounwind ; <i32> [#uses=1]
%tmp3 = or i32 %x, -5 ; <i32> [#uses=1]
%tmp5 = urem i32 251, %tmp3 ; <i32> [#uses=1]
%tmp6 = icmp ne i32 %tmp5, 0 ; <i1> [#uses=1]
%tmp67 = zext i1 %tmp6 to i32 ; <i32> [#uses=1]
%tmp9 = urem i32 %tmp67, 95 ; <i32> [#uses=1]
%tmp10 = and i32 %tmp9, 1 ; <i32> [#uses=1]
%tmp12 = icmp eq i32 %tmp10, 0 ; <i1> [#uses=1]
br i1 %tmp12, label %bb14, label %bb
%x = call i32 @func_11() nounwind
%tmp3 = or i32 %x, -5
%tmp5 = urem i32 251, %tmp3
%tmp6 = icmp ne i32 %tmp5, 0
%tmp67 = zext i1 %tmp6 to i32
%tmp9 = urem i32 %tmp67, 95
%tmp10 = and i32 %tmp9, 1
%tmp12 = icmp eq i32 %tmp10, 0
br i1 %tmp12, label %bb14, label %bb
bb: ; preds = %entry
br label %bb15
bb:
br label %bb15
bb14: ; preds = %entry
br label %bb15
bb14:
br label %bb15
bb15: ; preds = %bb14, %bb
%iftmp.0.0 = phi i8* [ getelementptr ([5 x i8], [5 x i8]* @.str1, i32 0, i32 0), %bb14 ], [ getelementptr ([5 x i8], [5 x i8]* @.str, i32 0, i32 0), %bb ] ; <i8*> [#uses=1]
%tmp17 = call i32 (i8*, ...) @printf( i8* %iftmp.0.0 ) nounwind ; <i32> [#uses=0]
ret i32 0
bb15:
%iftmp.0.0 = phi i8* [ getelementptr ([5 x i8], [5 x i8]* @.str1, i32 0, i32 0), %bb14 ], [ getelementptr ([5 x i8], [5 x i8]* @.str, i32 0, i32 0), %bb ]
%tmp17 = call i32 (i8*, ...) @printf(i8* %iftmp.0.0) nounwind
ret i32 0
}
; CHECK-LABEL: define i32 @main(
; CHECK: call i32 @func_11()
; CHECK-NEXT: br i1 false, label %bb14, label %bb
declare i32 @func_11()
declare i32 @printf(i8*, ...) nounwind
declare i32 @printf(i8*, ...) nounwind

14
llvm/test/Transforms/InstSimplify/rem.ll
View File

@ -49,3 +49,17 @@ define i32 @rem3(i32 %x, i32 %n) {
%mod1 = urem i32 %mod, %n
ret i32 %mod1
}
declare i32 @external()
define i32 @rem4() {
; CHECK-LABEL: @rem4(
; CHECK: [[CALL:%.*]] = call i32 @external(), !range !0
; CHECK-NEXT: ret i32 [[CALL]]
;
%call = call i32 @external(), !range !0
%urem = urem i32 %call, 3
ret i32 %urem
}
!0 = !{i32 0, i32 3}