[cfe-commits] r167416 - /cfe/trunk/lib/CodeGen/TargetInfo.cpp

[Manman Ren]

Author: mren
Date: Mon Nov  5 16:42:46 2012
New Revision: 167416

URL: http://llvm.org/viewvc/llvm-project?rev=167416&view=rev
Log:
ARM byval: when type alignment is bigger than ABI alignment, we can't guarantee
the type alignment of the byval argument. This patch will disable byval in this case,
it also increases the size threshold for turning on byval.

A backend fix will be attempted.

rdar://12596507

Modified:
    cfe/trunk/lib/CodeGen/TargetInfo.cpp

Modified: cfe/trunk/lib/CodeGen/TargetInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/TargetInfo.cpp?rev=167416&r1=167415&r2=167416&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/TargetInfo.cpp (original)
+++ cfe/trunk/lib/CodeGen/TargetInfo.cpp Mon Nov  5 16:42:46 2012
@@ -3220,8 +3220,16 @@
   }
 
   // Support byval for ARM.
-  if (getContext().getTypeSizeInChars(Ty) > CharUnits::fromQuantity(64) ||
-      getContext().getTypeAlign(Ty) > 64) {
+  // The ABI alignment for APCS is 4-byte and for AAPCS at least 4-byte and at most 8-byte.
+  // Byval can't handle the case where type alignment is bigger than ABI alignment.
+  // We also increase the threshold for byval due to its overhead.
+  uint64_t ABIAlign = 4;
+  uint64_t TyAlign = getContext().getTypeAlign(Ty) / 8;
+  if (getABIKind() == ARMABIInfo::AAPCS_VFP ||
+      getABIKind() == ARMABIInfo::AAPCS)
+    ABIAlign = std::min(std::max(TyAlign, (uint64_t)4), (uint64_t)8);
+  if (getContext().getTypeSizeInChars(Ty) > CharUnits::fromQuantity(64*8) &&
+      TyAlign <= ABIAlign) {
     return ABIArgInfo::getIndirect(0, /*ByVal=*/true);
   }