[Assembler] Add test for !srcloc references in assembler diags

[sanwou01]

Summary

clang adds !srcloc metadata to inline assembly in LLVM bitcode generated
for inline assembly in C. The value of this !srcloc is passed to the
diagnostics handler if the inline assembly generates a diagnostic.
clang is able to turn this cookie back to a location in the C source
file.

To test this functionality without a dependency, make llc print the
!srcloc metadata if it is present. The added test uses this mechanism
to test that the correct !srclocs are passed to the diag handler.

[mehdi_amini]

tools/llc/llc.cpp

266 ↗

(On Diff #89117)

That could be noisy, wouldn't it? Maybe have an option to enable displaying this in llc?
Also, it this note following another message? What does it look like? (the note alone wouldn't be great).

[sanwou01]

tools/llc/llc.cpp

266 ↗

(On Diff #89117)

I did consider the noisiness of this message. Consider, the note is only printed if

• !srcloc metadata is present; only the case in a clang-generated .ll file from a file containing inline assembly, and
• a diagnostic is emitted from IR with !srcloc metadata, and
• the .ll file is assembled using llc; none of the other tools are affected.

In short, this should not be very noisy.

Also, the note is always associated with the diagnostic printed by the SMD.print() above, so it is always printed after the proper diagnostic, e.g.:

<inline asm>:1:1: error: unknown instruction
              wibble
              ^
note: !srcloc = 107

Is this acceptable?

[sanwou01]

Could I please ask someone to have a look if they have a moment?

aka

ping :-)

[mehdi_amini]

LGMT

tools/llc/llc.cpp

266 ↗

(On Diff #89117)

Is this acceptable?

Sure! Thanks.

llvm/trunk/test/MC/ARM/inline-asm-srcloc.ll

+; RUN: not llc -filetype=obj 2>&1 -o /dev/null < %s | FileCheck %s
+
+; ModuleID = '/scratch/llvm/master/tools/clang/test/Misc/inline-asm-diags.c'
+source_filename = "/scratch/llvm/master/tools/clang/test/Misc/inline-asm-diags.c"
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "armv7-arm-none-eabi"
+
+; Function Attrs: noinline nounwind
+define void @foo2() #0 {
+entry:
+  call void asm sideeffect " wibble", ""() #1, !srcloc !3
+; CHECK: note: !srcloc = 107
+  ret void
+}
+
+; Function Attrs: noinline nounwind
+define void @foo() #0 {
+entry:
+  call void asm sideeffect " .word -bar", ""() #1, !srcloc !4
+; CHECK: note: !srcloc = 181
+  call void asm sideeffect " .word -foo", ""() #1, !srcloc !5
+; CHECK: note: !srcloc = 257
+  ret void
+}
+
+attributes #0 = { noinline nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="cortex-a8" "target-features"="+dsp,+neon,+strict-align,+vfp3" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind }
+
+!llvm.module.flags = !{!0, !1}
+!llvm.ident = !{!2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 1, !"min_enum_size", i32 4}
+!2 = !{!"clang version 5.0.0 "}
+!3 = !{i32 107}
+!4 = !{i32 181}
+!5 = !{i32 257}

llvm/trunk/tools/llc/llc.cpp

static void DiagnosticHandler(const DiagnosticInfo &DI, void *Context) {
 
   DiagnosticPrinterRawOStream DP(errs());
   errs() << LLVMContext::getDiagnosticMessagePrefix(DI.getSeverity()) << ": ";
   DI.print(DP);
   errs() << "\n";
 }
 
 static void InlineAsmDiagHandler(const SMDiagnostic &SMD, void *Context,
-                                 unsigned) {
+                                 unsigned LocCookie) {
   bool *HasError = static_cast<bool *>(Context);
   if (SMD.getKind() == SourceMgr::DK_Error)
     *HasError = true;
 
   SMD.print(nullptr, errs());
+
+  // For testing purposes, we print the LocCookie here.
+  if (LocCookie)
+    errs() << "note: !srcloc = " << LocCookie << "\n";
 }
 
 // main - Entry point for the llc compiler.
 //
 int main(int argc, char **argv) {
   sys::PrintStackTraceOnErrorSignal(argv[0]);
   PrettyStackTraceProgram X(argc, argv);