Simplify atomic load/store IRGen.
Also fixes a couple minor bugs along the way; see testcases.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@186049 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGAtomic.cpp b/lib/CodeGen/CGAtomic.cpp
index 1fc4f94..b5b74d2 100644
--- a/lib/CodeGen/CGAtomic.cpp
+++ b/lib/CodeGen/CGAtomic.cpp
@@ -93,7 +93,7 @@
return (ValueSizeInBits != AtomicSizeInBits);
}
- void emitMemSetZeroIfNecessary(LValue dest) const;
+ bool emitMemSetZeroIfNecessary(LValue dest) const;
llvm::Value *getAtomicSizeValue() const {
CharUnits size = CGF.getContext().toCharUnitsFromBits(AtomicSizeInBits);
@@ -164,21 +164,22 @@
return !isFullSizeType(CGF.CGM, type->getStructElementType(0),
AtomicSizeInBits / 2);
- // Just be pessimistic about aggregates.
+ // Padding in structs has an undefined bit pattern. User beware.
case TEK_Aggregate:
- return true;
+ return false;
}
llvm_unreachable("bad evaluation kind");
}
-void AtomicInfo::emitMemSetZeroIfNecessary(LValue dest) const {
+bool AtomicInfo::emitMemSetZeroIfNecessary(LValue dest) const {
llvm::Value *addr = dest.getAddress();
if (!requiresMemSetZero(addr->getType()->getPointerElementType()))
- return;
+ return false;
CGF.Builder.CreateMemSet(addr, llvm::ConstantInt::get(CGF.Int8Ty, 0),
AtomicSizeInBits / 8,
dest.getAlignment().getQuantity());
+ return true;
}
static void
@@ -715,30 +716,13 @@
RValue AtomicInfo::convertTempToRValue(llvm::Value *addr,
AggValueSlot resultSlot) const {
- if (EvaluationKind == TEK_Aggregate) {
- // Nothing to do if the result is ignored.
- if (resultSlot.isIgnored()) return resultSlot.asRValue();
-
- assert(resultSlot.getAddr() == addr || hasPadding());
-
- // In these cases, we should have emitted directly into the result slot.
- if (!hasPadding() || resultSlot.isValueOfAtomic())
- return resultSlot.asRValue();
-
- // Otherwise, fall into the common path.
- }
+ if (EvaluationKind == TEK_Aggregate)
+ return resultSlot.asRValue();
// Drill into the padding structure if we have one.
if (hasPadding())
addr = CGF.Builder.CreateStructGEP(addr, 0);
- // If we're emitting to an aggregate, copy into the result slot.
- if (EvaluationKind == TEK_Aggregate) {
- CGF.EmitAggregateCopy(resultSlot.getAddr(), addr, getValueType(),
- resultSlot.isVolatile());
- return resultSlot.asRValue();
- }
-
// Otherwise, just convert the temporary to an r-value using the
// normal conversion routine.
return CGF.convertTempToRValue(addr, getValueType());
@@ -752,10 +736,7 @@
// Check whether we should use a library call.
if (atomics.shouldUseLibcall()) {
llvm::Value *tempAddr;
- if (resultSlot.isValueOfAtomic()) {
- assert(atomics.getEvaluationKind() == TEK_Aggregate);
- tempAddr = resultSlot.getPaddedAtomicAddr();
- } else if (!resultSlot.isIgnored() && !atomics.hasPadding()) {
+ if (!resultSlot.isIgnored()) {
assert(atomics.getEvaluationKind() == TEK_Aggregate);
tempAddr = resultSlot.getAddr();
} else {
@@ -819,16 +800,10 @@
llvm::Value *temp;
bool tempIsVolatile = false;
CharUnits tempAlignment;
- if (atomics.getEvaluationKind() == TEK_Aggregate &&
- (!atomics.hasPadding() || resultSlot.isValueOfAtomic())) {
+ if (atomics.getEvaluationKind() == TEK_Aggregate) {
assert(!resultSlot.isIgnored());
- if (resultSlot.isValueOfAtomic()) {
- temp = resultSlot.getPaddedAtomicAddr();
- tempAlignment = atomics.getAtomicAlignment();
- } else {
- temp = resultSlot.getAddr();
- tempAlignment = atomics.getValueAlignment();
- }
+ temp = resultSlot.getAddr();
+ tempAlignment = atomics.getValueAlignment();
tempIsVolatile = resultSlot.isVolatile();
} else {
temp = CreateMemTemp(atomics.getAtomicType(), "atomic-load-temp");
@@ -996,13 +971,11 @@
}
case TEK_Aggregate: {
- // Memset the buffer first if there's any possibility of
- // uninitialized internal bits.
- atomics.emitMemSetZeroIfNecessary(dest);
-
- // HACK: whether the initializer actually has an atomic type
- // doesn't really seem reliable right now.
+ // Fix up the destination if the initializer isn't an expression
+ // of atomic type.
+ bool Zeroed = false;
if (!init->getType()->isAtomicType()) {
+ Zeroed = atomics.emitMemSetZeroIfNecessary(dest);
dest = atomics.projectValue(dest);
}
@@ -1010,7 +983,10 @@
AggValueSlot slot = AggValueSlot::forLValue(dest,
AggValueSlot::IsNotDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
- AggValueSlot::IsNotAliased);
+ AggValueSlot::IsNotAliased,
+ Zeroed ? AggValueSlot::IsZeroed :
+ AggValueSlot::IsNotZeroed);
+
EmitAggExpr(init, slot);
return;
}