Fix Thumb __builtin_longjmp with integrated assembler. <rdar://problem/11203543>

The tLDRr instruction with the last register operand set to the zero register
prints in assembly as if no register was specified, and the assembler encodes
it as a tLDRi instruction with a zero immediate.  With the integrated assembler,
that zero register gets emitted as "r0", so we get "ldr rx, [ry, r0]" which
is broken.  Emit the instruction as tLDRi with a zero immediate.  I don't
know if there's a good way to write a testcase for this.  Suggestions welcome.

Opportunities for follow-up work:
1) The asm printer should complain if a non-optional register operand is set
   to the zero register, instead of silently dropping it.
2) The integrated assembler should complain in the same situation, instead of
   silently emitting the operand as "r0".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154261 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMAsmPrinter.cpp b/lib/Target/ARM/ARMAsmPrinter.cpp
index 100ecf08785717a9c218efc8aee220e22b7dfd5e..9df5f4c10654d04a104299406b88801514912a35 100644 (file)
--- a/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -1976,10 +1976,10 @@ void ARMAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     }
     {
       MCInst TmpInst;
-      TmpInst.setOpcode(ARM::tLDRr);
+      TmpInst.setOpcode(ARM::tLDRi);
       TmpInst.addOperand(MCOperand::CreateReg(ARM::R7));
       TmpInst.addOperand(MCOperand::CreateReg(SrcReg));
-      TmpInst.addOperand(MCOperand::CreateReg(0));
+      TmpInst.addOperand(MCOperand::CreateImm(0));
       // Predicate.
       TmpInst.addOperand(MCOperand::CreateImm(ARMCC::AL));
       TmpInst.addOperand(MCOperand::CreateReg(0));