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Fix PR9820: a read-only call differs from a load in that a load doesn't

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return the pointer being dereferenced, it returns the pointee, but a call
might return the pointer itself.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130979 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands 2011-05-06 10:30:37 +00:00
parent 5e926ac651
commit 5389210e63
2 changed files with 35 additions and 6 deletions
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15
lib/Transforms/Scalar/ScalarReplAggregates.cpp
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@ -2481,19 +2481,22 @@ static bool isOnlyCopiedFromConstantGlobal(Value *V, MemTransferInst *&TheCopy,
}
if (CallSite CS = U) {
// If this is a readonly/readnone call site, then we know it is just a
// load and we can ignore it.
if (CS.onlyReadsMemory())
continue;
// If this is the function being called then we treat it like a load and
// ignore it.
if (CS.isCallee(UI))
continue;
// If this is a readonly/readnone call site, then we know it is just a
// load (but one that potentially returns the value itself), so we can
// ignore it if we know that the value isn't captured.
unsigned ArgNo = CS.getArgumentNo(UI);
if (CS.onlyReadsMemory() &&
(CS.getInstruction()->use_empty() ||
CS.paramHasAttr(ArgNo+1, Attribute::NoCapture)))
continue;
// If this is being passed as a byval argument, the caller is making a
// copy, so it is only a read of the alloca.
unsigned ArgNo = CS.getArgumentNo(UI);
if (CS.paramHasAttr(ArgNo+1, Attribute::ByVal))
continue;
}

26
test/Transforms/ScalarRepl/2011-05-06-CapturedAlloca.ll Normal file
View File

@ -0,0 +1,26 @@
; RUN: opt < %s -instcombine -S | FileCheck %s
; PR9820
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-unknown-linux-gnu"
@func_1.l_10 = internal unnamed_addr constant [4 x i32] [i32 1, i32 0, i32 0, i32 0], align 16
define i32* @noop(i32* %p_29) nounwind readnone {
entry:
ret i32* %p_29
}
define i32 @main() nounwind {
entry:
%l_10 = alloca [4 x i32], align 16
%tmp = bitcast [4 x i32]* %l_10 to i8*
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %tmp, i8* bitcast ([4 x i32]* @func_1.l_10 to i8*), i64 16, i32 16, i1 false)
; CHECK: call void @llvm.memcpy
%arrayidx = getelementptr inbounds [4 x i32]* %l_10, i64 0, i64 0
%call = call i32* @noop(i32* %arrayidx)
store i32 0, i32* %call
ret i32 0
}
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) nounwind