Revert "Stop increasing alignment of externally-visible globals on ELF platforms."
This reverts commit r257719, due to PR26144.
llvm-svn: 257775
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 91b3499..d2793e5 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -944,31 +944,37 @@
static unsigned enforceKnownAlignment(Value *V, unsigned Align,
unsigned PrefAlign,
const DataLayout &DL) {
- assert(PrefAlign > Align);
-
V = V->stripPointerCasts();
if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
- assert(AI->getAlignment() <= Align);
// If the preferred alignment is greater than the natural stack alignment
// then don't round up. This avoids dynamic stack realignment.
if (DL.exceedsNaturalStackAlignment(PrefAlign))
return Align;
+ // If there is a requested alignment and if this is an alloca, round up.
+ if (AI->getAlignment() >= PrefAlign)
+ return AI->getAlignment();
AI->setAlignment(PrefAlign);
return PrefAlign;
}
if (auto *GO = dyn_cast<GlobalObject>(V)) {
- assert(GO->getAlignment() <= Align);
// If there is a large requested alignment and we can, bump up the alignment
// 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->canIncreaseAlignment())
+ if (!GO->isStrongDefinitionForLinker())
return Align;
- GO->setAlignment(PrefAlign);
- return PrefAlign;
+ if (GO->getAlignment() >= PrefAlign)
+ return GO->getAlignment();
+ // We can only increase the alignment of the global if it has no alignment
+ // specified or if it is not assigned a section. If it is assigned a
+ // section, the global could be densely packed with other objects in the
+ // section, increasing the alignment could cause padding issues.
+ if (!GO->hasSection() || GO->getAlignment() == 0)
+ GO->setAlignment(PrefAlign);
+ return GO->getAlignment();
}
return Align;