diff options
| -rw-r--r-- | lib/CodeGen/AsmPrinter/AsmPrinter.cpp | 10 | ||||
| -rw-r--r-- | test/CodeGen/X86/alignment.ll | 18 | ||||
| -rw-r--r-- | test/CodeGen/X86/unaligned-load.ll | 1 |
3 files changed, 28 insertions, 1 deletions
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp index 4660e1b2cc..6fc883359b 100644 --- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp +++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp @@ -228,7 +228,15 @@ void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) { const TargetData *TD = TM.getTargetData(); unsigned Size = TD->getTypeAllocSize(GV->getType()->getElementType()); - unsigned AlignLog = TD->getPreferredAlignmentLog(GV); + + // If the alignment is specified, we *must* obey it. Overaligning a global + // with a specified alignment is a prompt way to break globals emitted to + // sections and expected to be contiguous (e.g. ObjC metadata). + unsigned AlignLog; + if (unsigned GVAlign = GV->getAlignment()) + AlignLog = Log2_32(GVAlign); + else + AlignLog = TD->getPreferredAlignmentLog(GV); // Handle common and BSS local symbols (.lcomm). if (GVKind.isCommon() || GVKind.isBSSLocal()) { diff --git a/test/CodeGen/X86/alignment.ll b/test/CodeGen/X86/alignment.ll new file mode 100644 index 0000000000..06a4f3f8e8 --- /dev/null +++ b/test/CodeGen/X86/alignment.ll @@ -0,0 +1,18 @@ +; RUN: llc %s -o - -mtriple=x86_64-linux-gnu | FileCheck %s + +; This cannot get rounded up to the preferred alignment (16) if they have an +; explicit alignment specified. +@GlobalA = global { [384 x i8] } zeroinitializer, align 8 + +; CHECK: .bss +; CHECK: .globl GlobalA +; CHECK: .align 8 +; CHECK: GlobalA: +; CHECK: .zero 384 + +; Common variables should not get rounded up to the preferred alignment (16) if +; they have an explicit alignment specified. +; PR6921 +@GlobalB = common global { [384 x i8] } zeroinitializer, align 8 + +; CHECK: .comm GlobalB,384,8
\ No newline at end of file diff --git a/test/CodeGen/X86/unaligned-load.ll b/test/CodeGen/X86/unaligned-load.ll index e210531068..b26097f31b 100644 --- a/test/CodeGen/X86/unaligned-load.ll +++ b/test/CodeGen/X86/unaligned-load.ll @@ -28,6 +28,7 @@ return: declare void @llvm.memcpy.i64(i8* nocapture, i8* nocapture, i64, i32) nounwind +; CORE2: .section ; CORE2: .align 3 ; CORE2-NEXT: _.str1: ; CORE2-NEXT: .asciz "DHRYSTONE PROGRAM, SOME STRING" |