Let each target decide byval alignment. For X86, it's 4-byte unless the aggregare contains SSE vector(s). For x86-64, it's max of 8 or alignment of the type.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46286 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 5c1ce69..9140539 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -672,6 +672,46 @@
allowUnalignedMemoryAccesses = true; // x86 supports it!
}
+/// getMaxByValAlign - Helper for getByValTypeAlignment to determine
+/// the desired ByVal argument alignment.
+static void getMaxByValAlign(const Type *Ty, unsigned &MaxAlign) {
+ if (MaxAlign == 16)
+ return;
+ if (const VectorType *VTy = dyn_cast<VectorType>(Ty)) {
+ if (VTy->getBitWidth() == 128)
+ MaxAlign = 16;
+ else if (VTy->getBitWidth() == 64)
+ if (MaxAlign < 8)
+ MaxAlign = 8;
+ } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
+ unsigned EltAlign = 0;
+ getMaxByValAlign(ATy->getElementType(), EltAlign);
+ if (EltAlign > MaxAlign)
+ MaxAlign = EltAlign;
+ } else if (const StructType *STy = dyn_cast<StructType>(Ty)) {
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
+ unsigned EltAlign = 0;
+ getMaxByValAlign(STy->getElementType(i), EltAlign);
+ if (EltAlign > MaxAlign)
+ MaxAlign = EltAlign;
+ if (MaxAlign == 16)
+ break;
+ }
+ }
+ return;
+}
+
+/// getByValTypeAlignment - Return the desired alignment for ByVal aggregate
+/// function arguments in the caller parameter area. For X86, aggregates
+/// that contains are placed at 16-byte boundaries while the rest are at
+/// 4-byte boundaries.
+unsigned X86TargetLowering::getByValTypeAlignment(const Type *Ty) const {
+ if (Subtarget->is64Bit())
+ return getTargetData()->getABITypeAlignment(Ty);
+ unsigned Align = 4;
+ getMaxByValAlign(Ty, Align);
+ return Align;
+}
/// getPICJumpTableRelocaBase - Returns relocation base for the given PIC
/// jumptable.