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[LLVM] Parametrize hardcoded behaviors in diagnostics error handling. #156439

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[LLVM] Parametrize hardcoded behaviors in diagnostics error handling. #156439

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fa0ed23
[LLVM] Introduce configurable halt actions on first unhandled diagnos…
mgcarrasco Sep 2, 2025
5a1cc08
[llc] Add option to disable llc-specific diagnostic handler
mgcarrasco Sep 2, 2025
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43 changes: 41 additions & 2 deletions llvm/lib/IR/LLVMContext.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,30 @@

using namespace llvm;

namespace opts {

enum class HaltOnFirstDiagErrorAction {
Exit,
Abort,
None,
};

static cl::opt<HaltOnFirstDiagErrorAction> HaltOnFirstDiagErrorOpt(
"halt-on-first-diag-error",
cl::desc(
"Halt action to take on the first unhandled diagnostic error reported"),
cl::values(
clEnumValN(
HaltOnFirstDiagErrorAction::Exit, "exit",
"Exit with error code 1 on first diagnostic with error severity"),
clEnumValN(HaltOnFirstDiagErrorAction::Abort, "abort",
"Abort with a stacktrace immediately on first diagnostic "
"with error severity"),
clEnumValN(HaltOnFirstDiagErrorAction::None, "none",
"Do not halt on first diagnostic with error severity")),
cl::init(HaltOnFirstDiagErrorAction::Exit), cl::Hidden);
} // namespace opts

static StringRef knownBundleName(unsigned BundleTagID) {
switch (BundleTagID) {
case LLVMContext::OB_deopt:
Expand Down Expand Up @@ -242,6 +266,19 @@ LLVMContext::getDiagnosticMessagePrefix(DiagnosticSeverity Severity) {
llvm_unreachable("Unknown DiagnosticSeverity");
}

static void handleHaltOnFirstDiagError() {
switch (opts::HaltOnFirstDiagErrorOpt) {
case opts::HaltOnFirstDiagErrorAction::Exit:
std::exit(1);
break;
case opts::HaltOnFirstDiagErrorAction::Abort:
std::abort();
break;
default:
break;
}
}

void LLVMContext::diagnose(const DiagnosticInfo &DI) {
if (auto *OptDiagBase = dyn_cast<DiagnosticInfoOptimizationBase>(&DI))
if (LLVMRemarkStreamer *RS = getLLVMRemarkStreamer())
Expand All @@ -264,8 +301,10 @@ void LLVMContext::diagnose(const DiagnosticInfo &DI) {
errs() << getDiagnosticMessagePrefix(DI.getSeverity()) << ": ";
DI.print(DP);
errs() << "\n";
if (DI.getSeverity() == DS_Error)
exit(1);

if (DI.getSeverity() == DS_Error) {
handleHaltOnFirstDiagError();
}
}

//===----------------------------------------------------------------------===//
Expand Down
25 changes: 25 additions & 0 deletions llvm/test/tools/llc/no-diagnostic-handler.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,25 @@
; COM: Test that the default behavior persists (the llc-specific handler prints all errors).
; RUN: not llc -mtriple=amdgcn -verify-machineinstrs=0 -global-isel=false < %s 2>&1 | FileCheck -check-prefix=ALL-ERRORS %s
; COM: Do not halt on the first error when the llc-specific handler is not loaded.
; RUN: not llc -mtriple=amdgcn -verify-machineinstrs=0 -global-isel=false -no-diag-handler -halt-on-first-diag-error=none < %s 2>&1 | FileCheck -check-prefix=ALL-ERRORS %s

; COM: Now halt on the first error by disabling the llc-specific handler and test the different halt actions
; RUN: not llc -mtriple=amdgcn -verify-machineinstrs=0 -global-isel=false -no-diag-handler -halt-on-first-diag-error=exit < %s 2>&1 | FileCheck -check-prefix=FIRST-ERROR %s
; COM: Same error message as in -halt-on-first-diag-error=exit but with a crash.
; RUN: not --crash llc -mtriple=amdgcn -verify-machineinstrs=0 -global-isel=false -no-diag-handler -halt-on-first-diag-error=abort < %s 2>&1 | FileCheck -check-prefix=FIRST-ERROR %s

; ALL-ERRORS: error: <unknown>:0:0: in function illegal_vgpr_to_sgpr_copy_i32 void (): illegal VGPR to SGPR copy
; FIRST-ERROR: error: <unknown>:0:0: in function illegal_vgpr_to_sgpr_copy_i32 void (): illegal VGPR to SGPR copy
define amdgpu_kernel void @illegal_vgpr_to_sgpr_copy_i32() #0 {
%vgpr = call i32 asm sideeffect "; def $0", "=${v1}"()
call void asm sideeffect "; use $0", "${s9}"(i32 %vgpr)
ret void
}

; ALL-ERRORS: error: <unknown>:0:0: in function illegal_vgpr_to_sgpr_copy_v2i32 void (): illegal VGPR to SGPR copy
; FIRST-ERROR-NOT: error: <unknown>:0:0: in function illegal_vgpr_to_sgpr_copy_v2i32 void (): illegal VGPR to SGPR copy
define amdgpu_kernel void @illegal_vgpr_to_sgpr_copy_v2i32() #0 {
%vgpr = call <2 x i32> asm sideeffect "; def $0", "=${v[0:1]}"()
call void asm sideeffect "; use $0", "${s[10:11]}"(<2 x i32> %vgpr)
ret void
}
11 changes: 9 additions & 2 deletions llvm/tools/llc/llc.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -213,6 +213,11 @@ static cl::opt<std::string> PassPipeline(
static cl::alias PassPipeline2("p", cl::aliasopt(PassPipeline),
cl::desc("Alias for -passes"));

static cl::opt<bool>
NoDiagHandler("no-diag-handler",
cl::desc("Do not load the llc-specific diagnostic handler."),
cl::init(false), cl::Hidden);

namespace {

std::vector<std::string> &getRunPassNames() {
Expand Down Expand Up @@ -384,8 +389,10 @@ int main(int argc, char **argv) {
LLVMContext Context;
Context.setDiscardValueNames(DiscardValueNames);

// Set a diagnostic handler that doesn't exit on the first error
Context.setDiagnosticHandler(std::make_unique<LLCDiagnosticHandler>());
if (!NoDiagHandler) {
// Set a diagnostic handler that doesn't exit on the first error
Context.setDiagnosticHandler(std::make_unique<LLCDiagnosticHandler>());
}
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Have you tried setting a DiagHandlerCallback ?

Your current proposal adds 2 options: one for everyone linking with LLVMContext, and another llc specific.

You could just keep one that is llc-specific (like, abort-on-error or something like that).
The idea is to keep the LLCDiagnosticHandler, but call:

if(AbortOnError) {
  Context.setDiagnosticHandlerCallBack(
    [](const DiagnosticInfo*, void*) { abort(1); },
    nullptr);
}

When an error is diagnosed, it would go through LLCDiagnosticHandler::handleDiagnostics which calls DiagnosticHandler::handleDiagnostics, which calls DiagnosticHandler::DiagHandlerCallback if it is setted, which in our case will call abort(1).

That would reduce the surface of the change to achieve the behavior you want.

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Unrelated to this, it's weird that LLCDiagnosticHandler::handleDiagnostics calls DiagnosticHandler::handleDiagnostics but ignores its result (if the diagnostic was handled by the callback), which is always true if the callback is set.


Expected<std::unique_ptr<ToolOutputFile>> RemarksFileOrErr =
setupLLVMOptimizationRemarks(Context, RemarksFilename, RemarksPasses,
Expand Down