Never use .lcomm on platforms where it does not accept an alignment

[oota-llvm.git] / lib / CodeGen / AsmPrinter / AsmPrinter.cpp

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 52840faf7c30b561426323d2ba27f005ffc9bbe3..72b2f0c62afab4f7ef9028ac00112c376672359d 100644 (file)
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -308,8 +308,13 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
       return;
     }
 
-    if (Align == 1 ||
-        MAI->getLCOMMDirectiveAlignmentType() != LCOMM::NoAlignment) {
+    // Use .lcomm only if it supports user-specified alignment.
+    // Otherwise, while it would still be correct to use .lcomm in some
+    // cases (e.g. when Align == 1), the external assembler might enfore
+    // some -unknown- default alignment behavior, which could cause
+    // spurious differences between external and integrated assembler.
+    // Prefer to simply fall back to .local / .comm in this case.
+    if (MAI->getLCOMMDirectiveAlignmentType() != LCOMM::NoAlignment) {
       // .lcomm _foo, 42
       OutStreamer.EmitLocalCommonSymbol(GVSym, Size, Align);
       return;