[CodeGen] fix alignment of JUMPTABLE_INSTS on v8M.base
Summary:
The attached test case fails with "fatal error: error in backend:
misaligned pc-relative fixup value" as the jump table is misaligned.
The EmitAlignment existed already for ARM and Thumb-1 code, but was
missing for Thumb-2.
The test checks that the fatal error disappears when generating an obj
file, as well as checking the align directive is there when producing an
asm file.
Reviewers: rengolin, grosbach, t.p.northover, jmolloy, SjoerdMeijer, samparker
Reviewed By: samparker
Subscribers: samparker, aemerson, llvm-commits
Differential Revision: https://reviews.llvm.org/D29650
llvm-svn: 294950
diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
index d77717e..eb0d410 100644
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -1142,6 +1142,11 @@
const MachineOperand &MO1 = MI->getOperand(1);
unsigned JTI = MO1.getIndex();
+ // Make sure the Thumb jump table is 4-byte aligned. This will be a nop for
+ // ARM mode tables.
+ EmitAlignment(2);
+
+ // Emit a label for the jump table.
MCSymbol *JTISymbol = GetARMJTIPICJumpTableLabel(JTI);
OutStreamer->EmitLabel(JTISymbol);