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ConstantFold: Check that truncating the other side is safe under a sext when trying to remove a sext from a compare.

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Fixes PR16462.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185284 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2013-06-30 13:47:43 +00:00
parent 58b6dc032a
commit 80c070493d
2 changed files with 19 additions and 5 deletions
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4
lib/IR/ConstantFold.cpp
View File

@ -1857,9 +1857,9 @@ Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
if (CE1Inverse == CE1Op0) {
// Check whether we can safely truncate the right hand side.
Constant *C2Inverse = ConstantExpr::getTrunc(C2, CE1Op0->getType());
if (ConstantExpr::getZExt(C2Inverse, C2->getType()) == C2) {
if (ConstantExpr::getCast(CE1->getOpcode(), C2Inverse,
C2->getType()) == C2)
return ConstantExpr::getICmp(pred, CE1Inverse, C2Inverse);
}
}
}
}

20
test/Transforms/InstCombine/2010-03-03-ExtElim.ll
View File

@ -1,5 +1,4 @@
; RUN: opt -instcombine -S < %s | FileCheck %s
; PR6486
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
target triple = "i386-unknown-linux-gnu"
@ -7,8 +6,8 @@ target triple = "i386-unknown-linux-gnu"
@g_92 = common global [2 x i32*] zeroinitializer, align 4 ; <[2 x i32*]*> [#uses=1]
@g_177 = constant i32** bitcast (i8* getelementptr (i8* bitcast ([2 x i32*]* @g_92 to i8*), i64 4) to i32**), align 4 ; <i32***> [#uses=1]
define i1 @test() nounwind {
; CHECK: @test
define i1 @PR6486() nounwind {
; CHECK: @PR6486
%tmp = load i32*** @g_177 ; <i32**> [#uses=1]
%cmp = icmp ne i32** null, %tmp ; <i1> [#uses=1]
%conv = zext i1 %cmp to i32 ; <i32> [#uses=1]
@ -16,3 +15,18 @@ define i1 @test() nounwind {
ret i1 %cmp1
; CHECK: ret i1 true
}
@d = common global i32 0, align 4
@a = common global [1 x i32] zeroinitializer, align 4
define i1 @PR16462_1() nounwind {
; CHECK: @PR16462_1
ret i1 icmp sgt (i32 sext (i16 trunc (i32 select (i1 icmp eq (i32* getelementptr inbounds ([1 x i32]* @a, i32 0, i32 0), i32* @d), i32 0, i32 1) to i16) to i32), i32 65535)
; CHECK: ret i1 icmp sgt (i32 sext (i16 trunc (i32 select (i1 icmp eq (i32* getelementptr inbounds ([1 x i32]* @a, i32 0, i32 0), i32* @d), i32 0, i32 1) to i16) to i32), i32 65535)
}
define i1 @PR16462_2() nounwind {
; CHECK: @PR16462_2
ret i1 icmp sgt (i32 sext (i16 trunc (i32 select (i1 icmp eq (i32* getelementptr inbounds ([1 x i32]* @a, i32 0, i32 0), i32* @d), i32 0, i32 1) to i16) to i32), i32 42)
; CHECK: ret i1 icmp sgt (i16 trunc (i32 select (i1 icmp eq (i32* getelementptr inbounds ([1 x i32]* @a, i32 0, i32 0), i32* @d), i32 0, i32 1) to i16), i16 42)
}