further clarify alignment of globals, fix instcombine
to not increase the alignment of globals with an assigned
alignment and section.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102476 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 5e98d5b..38e7b6e 100644
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -59,29 +59,32 @@
// Treat this like a bitcast.
return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
}
- break;
+ return Align;
+ }
+ case Instruction::Alloca: {
+ AllocaInst *AI = cast<AllocaInst>(V);
+ // 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 (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
// If there is a large requested alignment and we can, bump up the alignment
// of the global.
- if (!GV->isDeclaration()) {
- if (GV->getAlignment() >= PrefAlign)
- Align = GV->getAlignment();
- else {
- GV->setAlignment(PrefAlign);
- Align = PrefAlign;
- }
- }
- } else if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
- // If there is a requested alignment and if this is an alloca, round up.
- if (AI->getAlignment() >= PrefAlign)
- Align = AI->getAlignment();
- else {
- AI->setAlignment(PrefAlign);
- Align = PrefAlign;
- }
+ if (GV->isDeclaration()) return Align;
+
+ if (GV->getAlignment() >= PrefAlign)
+ return GV->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 (!GV->hasSection() || GV->getAlignment() == 0)
+ GV->setAlignment(PrefAlign);
+ return GV->getAlignment();
}
return Align;