Respect per-target debug options (#6193)

* Base compiler options for targets on target-specific compiler options

Before this change, the target compiler options were based on the linkage-wide compiler
options, which where later again inherited from (basically a no-op).

With this change, the target-specific compiler options are added first, and then
the linkage-wide comnpiler options are inherited from.

* Remove debug instructions if target-specific setting is NONE

This helps to address #6092.

* Make sure the linkage debug info level is sufficient for each target

This closes #6092.

4 files changed, 73 insertions, 1 deletions

diff --git a/source/slang/slang-emit.cpp b/source/slang/slang-emit.cpp
index d8594ffdd..70521c7ee 100644
--- a/source/slang/slang-emit.cpp
+++ b/source/slang/slang-emit.cpp
@@ -94,6 +94,7 @@
 #include "slang-ir-ssa-simplification.h"
 #include "slang-ir-ssa.h"
 #include "slang-ir-string-hash.h"
+#include "slang-ir-strip-debug-info.h"
 #include "slang-ir-strip-default-construct.h"
 #include "slang-ir-strip-legalization-insts.h"
 #include "slang-ir-synthesize-active-mask.h"
@@ -301,6 +302,7 @@ struct LinkingAndOptimizationOptions
 //
 struct RequiredLoweringPassSet
 {
+    bool debugInfo;
     bool resultType;
     bool optionalType;
     bool combinedTextureSamplers;
@@ -332,6 +334,13 @@ void calcRequiredLoweringPassSet(
 {
     switch (inst->getOp())
     {
+    case kIROp_DebugValue:
+    case kIROp_DebugVar:
+    case kIROp_DebugLine:
+    case kIROp_DebugLocationDecoration:
+    case kIROp_DebugSource:
+        result.debugInfo = true;
+        break;
     case kIROp_ResultType:
         result.resultType = true;
         break;
@@ -584,6 +593,7 @@ Result linkAndOptimizeIR(
     auto target = codeGenContext->getTargetFormat();
     auto targetRequest = codeGenContext->getTargetReq();
     auto targetProgram = codeGenContext->getTargetProgram();
+    auto targetCompilerOptions = targetRequest->getOptionSet();
 
     // Get the artifact desc for the target
     const auto artifactDesc = ArtifactDescUtil::makeDescForCompileTarget(asExternal(target));
@@ -615,6 +625,13 @@ Result linkAndOptimizeIR(
     RequiredLoweringPassSet requiredLoweringPassSet = {};
     calcRequiredLoweringPassSet(requiredLoweringPassSet, codeGenContext, irModule->getModuleInst());
 
+    // Debug info is added by the front-end, and therefore needs to be stripped out by targets that
+    // opt out of debug info.
+    if (requiredLoweringPassSet.debugInfo &&
+        (targetCompilerOptions.getIntOption(CompilerOptionName::DebugInformation) ==
+         SLANG_DEBUG_INFO_LEVEL_NONE))
+        stripDebugInfo(irModule);
+
     if (!isKhronosTarget(targetRequest) && requiredLoweringPassSet.glslSSBO)
         lowerGLSLShaderStorageBufferObjectsToStructuredBuffers(irModule, sink);
 
diff --git a/source/slang/slang-ir-strip-debug-info.cpp b/source/slang/slang-ir-strip-debug-info.cpp
new file mode 100644
index 000000000..8b2a07663
--- /dev/null
+++ b/source/slang/slang-ir-strip-debug-info.cpp
@@ -0,0 +1,33 @@
+#include "slang-ir-strip-debug-info.h"
+
+#include "slang-ir-insts.h"
+
+namespace Slang
+{
+static void findDebugInfo(IRInst* inst, List<IRInst*>& debugInstructions)
+{
+    switch (inst->getOp())
+    {
+    case kIROp_DebugValue:
+    case kIROp_DebugVar:
+    case kIROp_DebugLine:
+    case kIROp_DebugLocationDecoration:
+    case kIROp_DebugSource:
+        debugInstructions.add(inst);
+        break;
+    default:
+        break;
+    }
+
+    for (auto child : inst->getChildren())
+        findDebugInfo(child, debugInstructions);
+}
+
+void stripDebugInfo(IRModule* irModule)
+{
+    List<IRInst*> debugInstructions;
+    findDebugInfo(irModule->getModuleInst(), debugInstructions);
+    for (auto debugInst : debugInstructions)
+        debugInst->removeAndDeallocate();
+}
+} // namespace Slang
diff --git a/source/slang/slang-ir-strip-debug-info.h b/source/slang/slang-ir-strip-debug-info.h
new file mode 100644
index 000000000..67aac1abb
--- /dev/null
+++ b/source/slang/slang-ir-strip-debug-info.h
@@ -0,0 +1,9 @@
+#pragma once
+
+namespace Slang
+{
+struct IRModule;
+
+/// Strip all debug info instructions from `irModule`
+void stripDebugInfo(IRModule* irModule);
+} // namespace Slang
diff --git a/source/slang/slang.cpp b/source/slang/slang.cpp
index 21944e4f3..ee0aa4c14 100644
--- a/source/slang/slang.cpp
+++ b/source/slang/slang.cpp
@@ -842,6 +842,16 @@ Session::createSession(slang::SessionDesc const& inDesc, slang::ISession** outSe
         }
     }
 
+    // If any target requires debug info, then we will need to enable debug info when lowering to
+    // target-agnostic IR. The target-agnostic IR will only include debug info if the linkage IR
+    // options specify that it should, so make sure the linkage debug info level is greater than or
+    // equal to that of any target.
+    DebugInfoLevel linkageDebugInfoLevel = linkage->m_optionSet.getDebugInfoLevel();
+    for (auto target : linkage->targets)
+        linkageDebugInfoLevel =
+            Math::Max(linkageDebugInfoLevel, target->getOptionSet().getDebugInfoLevel());
+    linkage->m_optionSet.set(CompilerOptionName::DebugInformation, linkageDebugInfoLevel);
+
     *outSession = asExternal(linkage.detach());
     return SLANG_OK;
 }
@@ -1337,7 +1347,10 @@ void Linkage::addTarget(slang::TargetDesc const& desc)
     optionSet.setProfile(Profile(desc.profile));
     optionSet.set(CompilerOptionName::LineDirectiveMode, LineDirectiveMode(desc.lineDirectiveMode));
     optionSet.set(CompilerOptionName::GLSLForceScalarLayout, desc.forceGLSLScalarBufferLayout);
-    optionSet.load(desc.compilerOptionEntryCount, desc.compilerOptionEntries);
+
+    CompilerOptionSet targetOptions;
+    targetOptions.load(desc.compilerOptionEntryCount, desc.compilerOptionEntries);
+    optionSet.overrideWith(targetOptions);
 }
 
 #if 0