JIT: Print debug location of inline asm and ignore DBG_VALUE instructions

[yaron.keren]

Summary

Two small enhancements for the JIT.

When JITting a large project such as Boost it's quite hard to figure out the problematic inline asm without debug location. This patch provides debug location printout before the JIT aborts due to inline asm. printDebugLoc() was exposed from MachineInstr.cpp and reused here.

If the JIT run with debug info, don't bomb on DBG_VALUE but ignore them.

[yaron.keren]

Ping?

[echristo]

You'll possibly want dbg_declare there too.

I think I'd like printDebugLoc to be somewhere else if we use it, but why not just print out the entire inline asm MachineInstr?

Also, you should probably move to MCJIT :)

[yaron.keren]

Printing the instruction is not needed as you'd usually want just the debug location to workaround.

Using dump() does the patch trivial not using printDebugLoc().

TargetOpcode has DBG_VALUE but not DBG_DECLARE ? how to add this?

[yaron.keren]

Hi, is this patch good to commit now?

[echristo]

Sadly looks like I was wrong about printing out the instruction - nothing else does it.

LGTM with that pulled back out.

[yaron.keren]

Meanwhile, DebugLoc gained a new print() method in r208177, so we can reuse it.

[yaron.keren]

Ping? just few lines.

[yaron.keren]

Committed r210201.

lib/Target/X86/X86CodeEmitter.cpp

     case TargetOpcode::INLINEASM:
       // We allow inline assembler nodes with empty bodies - they can
       // implicitly define registers, which is ok for JIT.
-      if (MI.getOperand(0).getSymbolName()[0])
+      if (MI.getOperand(0).getSymbolName()[0]) {
+        DebugLoc DL = MI.getDebugLoc();
+        DL.print(MI.getParent()->getParent()->getFunction()->getContext(),
+                 llvm::errs());
         report_fatal_error("JIT does not support inline asm!");
+      }
       break;
+    case TargetOpcode::DBG_VALUE:
     case TargetOpcode::CFI_INSTRUCTION:
       break;
     case TargetOpcode::GC_LABEL: