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Fix invalid cast in instcombine UMul/ZExt idiom

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Fixes https://bugs.llvm.org/show_bug.cgi?id=25454

Do not assume IRBuilder creates Instruction where it can create Value.
Do not assume idiom operands are constant, leave generalisation ot the IRBuilder.

Differential Revision: https://reviews.llvm.org/D35114


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307554 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Serge Guelton 2017-07-10 16:51:40 +00:00
parent b6988767a8
commit 65eefa7f01
2 changed files with 36 additions and 6 deletions
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13
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -3856,17 +3856,18 @@ static Instruction *processUMulZExtIdiom(ICmpInst &I, Value *MulVal,
} else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) {
assert(BO->getOpcode() == Instruction::And);
// Replace (mul & mask) --> zext (mul.with.overflow & short_mask)
ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1));
APInt ShortMask = CI->getValue().trunc(MulWidth);
Value *ShortMask =
Builder.CreateTrunc(BO->getOperand(1), Builder.getIntNTy(MulWidth));
Value *ShortAnd = Builder.CreateAnd(Mul, ShortMask);
Instruction *Zext =
cast<Instruction>(Builder.CreateZExt(ShortAnd, BO->getType()));
IC.Worklist.Add(Zext);
Value *Zext = Builder.CreateZExt(ShortAnd, BO->getType());
if (auto *ZextI = dyn_cast<Instruction>(Zext))
IC.Worklist.Add(ZextI);
IC.replaceInstUsesWith(*BO, Zext);
} else {
llvm_unreachable("Unexpected Binary operation");
}
IC.Worklist.Add(cast<Instruction>(U));
if (auto *UI = dyn_cast<Instruction>(U))
IC.Worklist.Add(UI);
}
}
if (isa<Instruction>(OtherVal))

29
test/Transforms/InstCombine/2017-07-07-UMul-ZExt.ll Normal file
View File

@ -0,0 +1,29 @@
; RUN: opt < %s -instcombine -S | FileCheck %s
; CHECK: llvm.umul.with.overflow
define i32 @sterix(i32, i8, i64) {
entry:
%conv = zext i32 %0 to i64
%conv1 = sext i8 %1 to i32
%mul = mul i32 %conv1, 1945964878
%sh_prom = trunc i64 %2 to i32
%shr = lshr i32 %mul, %sh_prom
%conv2 = zext i32 %shr to i64
%mul3 = mul nuw nsw i64 %conv, %conv2
%conv6 = and i64 %mul3, 4294967295
%tobool = icmp ne i64 %conv6, %mul3
br i1 %tobool, label %lor.end, label %lor.rhs
lor.rhs:
%and = and i64 %2, %mul3
%conv4 = trunc i64 %and to i32
%tobool7 = icmp ne i32 %conv4, 0
%lnot = xor i1 %tobool7, true
br label %lor.end
lor.end:
%3 = phi i1 [ true, %entry ], [ %lnot, %lor.rhs ]
%conv8 = zext i1 %3 to i32
ret i32 %conv8
}