[llvm-commits] [llvm-gcc-4.2] r63288 - /llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp

[Chris Lattner]

Author: lattner
Date: Thu Jan 29 01:50:02 2009
New Revision: 63288

URL: http://llvm.org/viewvc/llvm-project?rev=63288&view=rev
Log:
If a FIELD_DECL says its alignment is 16 bytes, and the base pointer
is only known to be 8-byte aligned, round up to 16 bytes.  I believe 
that this is always safe.  Duncan, I would appreciate the review.

Modified:
    llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp

Modified: llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp?rev=63288&r1=63287&r2=63288&view=diff

==============================================================================
--- llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp (original)
+++ llvm-gcc-4.2/trunk/gcc/llvm-convert.cpp Thu Jan 29 01:50:02 2009
@@ -1161,7 +1161,7 @@
   // Constants.
   case LABEL_DECL: {
     Value *Ptr = TreeConstantToLLVM::EmitLV_LABEL_DECL(exp);
-    return LValue(Ptr, DECL_ALIGN(exp) / 8);
+    return LValue(Ptr, DECL_ALIGN_UNIT(exp));
   }
   case COMPLEX_CST: {
     Value *Ptr = TreeConstantToLLVM::EmitLV_COMPLEX_CST(exp);
@@ -6198,9 +6198,15 @@
       LVAlign = MinAlign(LVAlign, Offset);
     }
     
-    // If the FIELD_DECL has an annotate attribute on it, emit it.
+    // If this field is at a constant offset, if the LLVM pointer really points
+    // to it, then we know that the pointer is at least as aligned as the field
+    // is required to be.  Try to round up our alignment info.
+    if (BitStart == 0 && // llvm pointer points to it.
+        !isBitfield(FieldDecl) &&  // bitfield computation might offset pointer.
+        DECL_ALIGN_UNIT(FieldDecl))
+      LVAlign = std::max(LVAlign, unsigned(DECL_ALIGN_UNIT(FieldDecl)));
     
-    // Handle annotate attribute on global.
+    // If the FIELD_DECL has an annotate attribute on it, emit it.
     if (lookup_attribute("annotate", DECL_ATTRIBUTES(FieldDecl)))
       FieldPtr = EmitFieldAnnotation(FieldPtr, FieldDecl);
   } else {