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Update enforceKnownAlignment after the isWeakForLinker semantic change

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Previously we would refrain from attempting to increase the linkage of
available_externally globals because they were considered weak for the
linker. Now they are treated more like a declaration instead of a weak
definition.

This was causing SSE alignment faults in Chromuim, when some code
assumed it could increase the alignment of a dllimported global that it
didn't control.  http://crbug.com/509256

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242091 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Kleckner 2015-07-14 00:11:08 +00:00
parent c249168837
commit b53f724f91
2 changed files with 23 additions and 14 deletions
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11
lib/Transforms/Utils/Local.cpp
View File

@ -900,13 +900,10 @@ static unsigned enforceKnownAlignment(Value *V, unsigned Align,
if (auto *GO = dyn_cast<GlobalObject>(V)) {
// If there is a large requested alignment and we can, bump up the alignment
// of the global.
if (GO->isDeclaration())
return Align;
// If the memory we set aside for the global may not be the memory used by
// the final program then it is impossible for us to reliably enforce the
// preferred alignment.
if (GO->isWeakForLinker())
// of the global. If the memory we set aside for the global may not be the
// memory used by the final program then it is impossible for us to reliably
// enforce the preferred alignment.
if (!GO->isStrongDefinitionForLinker())
return Align;
if (GO->getAlignment() >= PrefAlign)

26
test/Transforms/InstCombine/align-external.ll
View File

@ -3,16 +3,14 @@
; Don't assume that external global variables or those with weak linkage have
; their preferred alignment. They may only have the ABI minimum alignment.
; CHECK: %s = shl i64 %a, 3
; CHECK: %r = or i64 %s, ptrtoint (i32* @A to i64)
; CHECK: %q = add i64 %r, 1
; CHECK: ret i64 %q
target datalayout = "i32:8:32"
@A = external global i32
@B = weak_odr global i32 0
@C = available_externally global <4 x i32> zeroinitializer, align 4
; CHECK: @C = available_externally global <4 x i32> zeroinitializer, align 4
define i64 @foo(i64 %a) {
%t = ptrtoint i32* @A to i64
%s = shl i64 %a, 3
@ -21,9 +19,23 @@ define i64 @foo(i64 %a) {
ret i64 %q
}
; CHECK-LABEL: define i64 @foo(i64 %a)
; CHECK: %s = shl i64 %a, 3
; CHECK: %r = or i64 %s, ptrtoint (i32* @A to i64)
; CHECK: %q = add i64 %r, 1
; CHECK: ret i64 %q
define i32 @bar() {
; CHECK-LABEL: @bar(
%r = load i32, i32* @B, align 1
; CHECK: align 1
ret i32 %r
}
; CHECK-LABEL: @bar()
; CHECK: align 1
define void @vec_store() {
store <4 x i32> <i32 0, i32 1, i32 2, i32 3>, <4 x i32>* @C, align 4
ret void
}
; CHECK: define void @vec_store()
; CHECK: store <4 x i32> <i32 0, i32 1, i32 2, i32 3>, <4 x i32>* @C, align 4