[CIR] -emit-cir should not implicitly enable the CIR pipeline #166916

mmha · 2025-11-07T10:08:13Z

Passing -emit-cir without -fclangir enables the CIR pipeline. This patch changes this to an error. Now -emit-cir requires -fclangir to be passed as well.

This is in preparation of a future patch that enables CIR as a source language in the driver. If a CIR module is passed on the command line this should also not implicitly enable the CIR pipeline for the rest of the compiler invocation (so C++ files passed on the same command line would be implicitly compiled using the CIR pipeline)

Passing -emit-cir without -fclangir enables the CIR pipeline. This patch changes this to an error. Now -emit-cir requires -fclangir to be passed as well. This is in preparation of a future patch that enables CIR as a source language in the driver. If a CIR module is passed on the command line this should also not implicitly enable the CIR pipeline for the rest of the compiler invocation (so C++ files passed on the same command line would be implicitly compiled using the CIR pipeline)

llvmbot · 2025-11-07T10:08:51Z

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-driver

Author: Morris Hafner (mmha)

Changes

Passing -emit-cir without -fclangir enables the CIR pipeline. This patch changes this to an error. Now -emit-cir requires -fclangir to be passed as well.

This is in preparation of a future patch that enables CIR as a source language in the driver. If a CIR module is passed on the command line this should also not implicitly enable the CIR pipeline for the rest of the compiler invocation (so C++ files passed on the same command line would be implicitly compiled using the CIR pipeline)

Full diff: https://github.com/llvm/llvm-project/pull/166916.diff

10 Files Affected:

(modified) clang/include/clang/Basic/DiagnosticDriverKinds.td (+3)
(modified) clang/include/clang/Basic/DiagnosticFrontendKinds.td (+3)
(modified) clang/lib/Frontend/CompilerInvocation.cpp (+9-1)
(modified) clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp (+12-4)
(modified) clang/test/CIR/CodeGen/builtin_prefetch.c (+2-2)
(modified) clang/test/CIR/CodeGen/dlti.c (+1-1)
(modified) clang/test/CIR/CodeGen/dlti_be.c (+1-1)
(modified) clang/test/CIR/CodeGen/module-asm.c (+1-1)
(added) clang/test/Driver/cir-flags-error.c (+11)
(added) clang/test/Driver/cir-input-without-fclangir.cir (+20)

diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 83980e3ac35b7..c47c2e5d42b90 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -887,6 +887,9 @@ def warn_missing_include_dirs : Warning<
 def err_drv_malformed_warning_suppression_mapping : Error<
   "failed to process suppression mapping file '%0': %1">;
 
+def err_drv_emit_cir_without_fclangir : Error<
+  "-emit-cir is only valid with -fclangir">;
+
 def warn_drv_openacc_without_cir
     : Warning<"OpenACC directives will result in no runtime behavior; use "
               "-fclangir to enable runtime effect">,
diff --git a/clang/include/clang/Basic/DiagnosticFrontendKinds.td b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
index 9e344160ff934..1ebea11dd5259 100644
--- a/clang/include/clang/Basic/DiagnosticFrontendKinds.td
+++ b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -136,6 +136,9 @@ def err_fe_action_not_available : Error<
     "action %0 not compiled in">;
 def err_fe_cir_not_built : Error<"clang IR support not available, rebuild "
                                  "clang with -DCLANG_ENABLE_CIR=ON">;
+def err_fe_cir_disabled : Error<
+  "trying to compile CIR module %0 with clang IR disabled; use "
+  "-fclangir to enable CIR pipeline">;
 def err_fe_invalid_multiple_actions : Error<
     "'%0' action ignored; '%1' action specified previously">;
 def err_fe_invalid_alignment : Error<
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index be7c1d367e082..59dae34f0fd3d 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -3139,9 +3139,17 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
   if (Opts.ProgramAction != frontend::GenerateModule && Opts.IsSystemModule)
     Diags.Report(diag::err_drv_argument_only_allowed_with) << "-fsystem-module"
                                                            << "-emit-module";
-  if (Args.hasArg(OPT_fclangir) || Args.hasArg(OPT_emit_cir))
+  if (Args.hasArg(OPT_fclangir))
     Opts.UseClangIRPipeline = true;
 
+#if CLANG_ENABLE_CIR
+  if (!Args.hasArg(OPT_fclangir) && Args.hasArg(OPT_emit_cir))
+    Diags.Report(diag::err_drv_emit_cir_without_fclangir);
+#else
+  if (Args.hasArg(OPT_emit_cir))
+    Diags.Report(diag::err_fe_cir_not_built);
+#endif
+
 #if CLANG_ENABLE_CIR
   if (Args.hasArg(OPT_clangir_disable_passes))
     Opts.ClangIRDisablePasses = true;
diff --git a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
index c8aad4daa1c10..25a89d465dcba 100644
--- a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
+++ b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
@@ -49,12 +49,20 @@ CreateFrontendBaseAction(CompilerInstance &CI) {
   StringRef Action("unknown");
   (void)Action;
 
+#if CLANG_ENABLE_CIR
   unsigned UseCIR = CI.getFrontendOpts().UseClangIRPipeline;
-  frontend::ActionKind Act = CI.getFrontendOpts().ProgramAction;
-  bool EmitsCIR = Act == EmitCIR;
 
-  if (!UseCIR && EmitsCIR)
-    llvm::report_fatal_error("-emit-cir and only valid when using -fclangir");
+  if (!UseCIR) {
+    FrontendInputFile *it =
+        llvm::find_if(CI.getFrontendOpts().Inputs, [](const auto &FIF) {
+          return FIF.getKind().getLanguage() == Language::CIR;
+        });
+    if (it != CI.getFrontendOpts().Inputs.end()) {
+      CI.getDiagnostics().Report(diag::err_fe_cir_disabled) << it->getFile();
+      return nullptr;
+    }
+  }
+#endif
 
   switch (CI.getFrontendOpts().ProgramAction) {
   case ASTDeclList:            return std::make_unique<ASTDeclListAction>();
diff --git a/clang/test/CIR/CodeGen/builtin_prefetch.c b/clang/test/CIR/CodeGen/builtin_prefetch.c
index cfe85b9ba8104..c38e179617b1d 100644
--- a/clang/test/CIR/CodeGen/builtin_prefetch.c
+++ b/clang/test/CIR/CodeGen/builtin_prefetch.c
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-cir %s -o - | FileCheck %s -check-prefix=CIR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o - | FileCheck %s -check-prefix=CIR
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o - | FileCheck %s -check-prefix=LLVM
-// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm %s -o - | FileCheck %s -check-prefix=OGCG
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o - | FileCheck %s -check-prefix=OGCG
 
 void foo(void *a) {
   __builtin_prefetch(a);        // rw=0, locality=3
diff --git a/clang/test/CIR/CodeGen/dlti.c b/clang/test/CIR/CodeGen/dlti.c
index 3fa15d2ab584f..0e58a37756b75 100644
--- a/clang/test/CIR/CodeGen/dlti.c
+++ b/clang/test/CIR/CodeGen/dlti.c
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-cir %s -o %t.cir
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
 // RUN: FileCheck --input-file=%t.cir %s --check-prefix=LITTLE
 
 void foo() {}
diff --git a/clang/test/CIR/CodeGen/dlti_be.c b/clang/test/CIR/CodeGen/dlti_be.c
index 918124ac0a237..b41e75466fe5f 100644
--- a/clang/test/CIR/CodeGen/dlti_be.c
+++ b/clang/test/CIR/CodeGen/dlti_be.c
@@ -1,5 +1,5 @@
 // REQUIRES: aarch64-registered-target
-// RUN: %clang_cc1 -triple aarch64_be-linux-gnu -emit-cir %s -o %t.cir
+// RUN: %clang_cc1 -triple aarch64_be-linux-gnu -fclangir -emit-cir %s -o %t.cir
 // RUN: FileCheck --input-file=%t.cir %s --check-prefix=BIG
 
 void foo() {}
diff --git a/clang/test/CIR/CodeGen/module-asm.c b/clang/test/CIR/CodeGen/module-asm.c
index e6cec5e0ee948..049a90f69d393 100644
--- a/clang/test/CIR/CodeGen/module-asm.c
+++ b/clang/test/CIR/CodeGen/module-asm.c
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-cir %s -o %t.cir 
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir 
 // RUN: FileCheck --input-file=%t.cir %s
 
 // CHECK:  cir.module_asm = [".globl bar", ".globl foo"]
diff --git a/clang/test/Driver/cir-flags-error.c b/clang/test/Driver/cir-flags-error.c
new file mode 100644
index 0000000000000..a76e3173fb33c
--- /dev/null
+++ b/clang/test/Driver/cir-flags-error.c
@@ -0,0 +1,11 @@
+// REQUIRES: cir-support
+
+// RUN: not %clang -emit-cir %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=EMIT_CIR_ERROR
+// EMIT_CIR_ERROR: error: -emit-cir is only valid with -fclangir
+
+// RUN: %clang -fclangir -emit-cir %s -o /dev/null 2>&1 | FileCheck %s --allow-empty -check-prefix=EMIT_CIR_OK
+// EMIT_CIR_OK-NOT: error: -emit-cir is only valid with -fclangir
+
+int main(void) {
+  return 0;
+}
diff --git a/clang/test/Driver/cir-input-without-fclangir.cir b/clang/test/Driver/cir-input-without-fclangir.cir
new file mode 100644
index 0000000000000..2c4354511a322
--- /dev/null
+++ b/clang/test/Driver/cir-input-without-fclangir.cir
@@ -0,0 +1,20 @@
+// RUN: not %clang %s -emit-llvm -o /dev/null 2>&1 | FileCheck %s -check-prefix=CIR_INPUT_ERROR
+// CIR_INPUT_ERROR: error: trying to compile CIR module {{.*}} with clang IR disabled; use -fclangir to enable CIR pipeline
+
+// RUN: %clang -fclangir %s -emit-llvm -o /dev/null 2>&1 | FileCheck %s --allow-empty -check-prefix=CIR_INPUT_OK
+// CIR_INPUT_OK-NOT: error: trying to compile CIR module
+
+// REQUIRES: x86-registered-target
+// REQUIRES: cir-support
+
+!s32i = !cir.int<s, 32>
+
+module attributes {cir.lang = #cir.lang<cxx>, cir.triple = "x86_64-unknown-linux-gnu"} {
+  cir.func @test_function() -> !s32i {
+    %0 = cir.alloca !s32i, !cir.ptr<!s32i>, ["__retval"] {alignment = 4 : i64}
+    %1 = cir.const #cir.int<42> : !s32i
+    cir.store %1, %0 : !s32i, !cir.ptr<!s32i>
+    %2 = cir.load %0 : !cir.ptr<!s32i>, !s32i
+    cir.return %2 : !s32i
+  }
+}

llvmbot · 2025-11-07T10:08:52Z

@llvm/pr-subscribers-clangir

Author: Morris Hafner (mmha)

Changes

Passing -emit-cir without -fclangir enables the CIR pipeline. This patch changes this to an error. Now -emit-cir requires -fclangir to be passed as well.

This is in preparation of a future patch that enables CIR as a source language in the driver. If a CIR module is passed on the command line this should also not implicitly enable the CIR pipeline for the rest of the compiler invocation (so C++ files passed on the same command line would be implicitly compiled using the CIR pipeline)

Full diff: https://github.com/llvm/llvm-project/pull/166916.diff

10 Files Affected:

(modified) clang/include/clang/Basic/DiagnosticDriverKinds.td (+3)
(modified) clang/include/clang/Basic/DiagnosticFrontendKinds.td (+3)
(modified) clang/lib/Frontend/CompilerInvocation.cpp (+9-1)
(modified) clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp (+12-4)
(modified) clang/test/CIR/CodeGen/builtin_prefetch.c (+2-2)
(modified) clang/test/CIR/CodeGen/dlti.c (+1-1)
(modified) clang/test/CIR/CodeGen/dlti_be.c (+1-1)
(modified) clang/test/CIR/CodeGen/module-asm.c (+1-1)
(added) clang/test/Driver/cir-flags-error.c (+11)
(added) clang/test/Driver/cir-input-without-fclangir.cir (+20)

diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 83980e3ac35b7..c47c2e5d42b90 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -887,6 +887,9 @@ def warn_missing_include_dirs : Warning<
 def err_drv_malformed_warning_suppression_mapping : Error<
   "failed to process suppression mapping file '%0': %1">;
 
+def err_drv_emit_cir_without_fclangir : Error<
+  "-emit-cir is only valid with -fclangir">;
+
 def warn_drv_openacc_without_cir
     : Warning<"OpenACC directives will result in no runtime behavior; use "
               "-fclangir to enable runtime effect">,
diff --git a/clang/include/clang/Basic/DiagnosticFrontendKinds.td b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
index 9e344160ff934..1ebea11dd5259 100644
--- a/clang/include/clang/Basic/DiagnosticFrontendKinds.td
+++ b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -136,6 +136,9 @@ def err_fe_action_not_available : Error<
     "action %0 not compiled in">;
 def err_fe_cir_not_built : Error<"clang IR support not available, rebuild "
                                  "clang with -DCLANG_ENABLE_CIR=ON">;
+def err_fe_cir_disabled : Error<
+  "trying to compile CIR module %0 with clang IR disabled; use "
+  "-fclangir to enable CIR pipeline">;
 def err_fe_invalid_multiple_actions : Error<
     "'%0' action ignored; '%1' action specified previously">;
 def err_fe_invalid_alignment : Error<
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index be7c1d367e082..59dae34f0fd3d 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -3139,9 +3139,17 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
   if (Opts.ProgramAction != frontend::GenerateModule && Opts.IsSystemModule)
     Diags.Report(diag::err_drv_argument_only_allowed_with) << "-fsystem-module"
                                                            << "-emit-module";
-  if (Args.hasArg(OPT_fclangir) || Args.hasArg(OPT_emit_cir))
+  if (Args.hasArg(OPT_fclangir))
     Opts.UseClangIRPipeline = true;
 
+#if CLANG_ENABLE_CIR
+  if (!Args.hasArg(OPT_fclangir) && Args.hasArg(OPT_emit_cir))
+    Diags.Report(diag::err_drv_emit_cir_without_fclangir);
+#else
+  if (Args.hasArg(OPT_emit_cir))
+    Diags.Report(diag::err_fe_cir_not_built);
+#endif
+
 #if CLANG_ENABLE_CIR
   if (Args.hasArg(OPT_clangir_disable_passes))
     Opts.ClangIRDisablePasses = true;
diff --git a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
index c8aad4daa1c10..25a89d465dcba 100644
--- a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
+++ b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
@@ -49,12 +49,20 @@ CreateFrontendBaseAction(CompilerInstance &CI) {
   StringRef Action("unknown");
   (void)Action;
 
+#if CLANG_ENABLE_CIR
   unsigned UseCIR = CI.getFrontendOpts().UseClangIRPipeline;
-  frontend::ActionKind Act = CI.getFrontendOpts().ProgramAction;
-  bool EmitsCIR = Act == EmitCIR;
 
-  if (!UseCIR && EmitsCIR)
-    llvm::report_fatal_error("-emit-cir and only valid when using -fclangir");
+  if (!UseCIR) {
+    FrontendInputFile *it =
+        llvm::find_if(CI.getFrontendOpts().Inputs, [](const auto &FIF) {
+          return FIF.getKind().getLanguage() == Language::CIR;
+        });
+    if (it != CI.getFrontendOpts().Inputs.end()) {
+      CI.getDiagnostics().Report(diag::err_fe_cir_disabled) << it->getFile();
+      return nullptr;
+    }
+  }
+#endif
 
   switch (CI.getFrontendOpts().ProgramAction) {
   case ASTDeclList:            return std::make_unique<ASTDeclListAction>();
diff --git a/clang/test/CIR/CodeGen/builtin_prefetch.c b/clang/test/CIR/CodeGen/builtin_prefetch.c
index cfe85b9ba8104..c38e179617b1d 100644
--- a/clang/test/CIR/CodeGen/builtin_prefetch.c
+++ b/clang/test/CIR/CodeGen/builtin_prefetch.c
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-cir %s -o - | FileCheck %s -check-prefix=CIR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o - | FileCheck %s -check-prefix=CIR
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o - | FileCheck %s -check-prefix=LLVM
-// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm %s -o - | FileCheck %s -check-prefix=OGCG
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o - | FileCheck %s -check-prefix=OGCG
 
 void foo(void *a) {
   __builtin_prefetch(a);        // rw=0, locality=3
diff --git a/clang/test/CIR/CodeGen/dlti.c b/clang/test/CIR/CodeGen/dlti.c
index 3fa15d2ab584f..0e58a37756b75 100644
--- a/clang/test/CIR/CodeGen/dlti.c
+++ b/clang/test/CIR/CodeGen/dlti.c
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-cir %s -o %t.cir
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
 // RUN: FileCheck --input-file=%t.cir %s --check-prefix=LITTLE
 
 void foo() {}
diff --git a/clang/test/CIR/CodeGen/dlti_be.c b/clang/test/CIR/CodeGen/dlti_be.c
index 918124ac0a237..b41e75466fe5f 100644
--- a/clang/test/CIR/CodeGen/dlti_be.c
+++ b/clang/test/CIR/CodeGen/dlti_be.c
@@ -1,5 +1,5 @@
 // REQUIRES: aarch64-registered-target
-// RUN: %clang_cc1 -triple aarch64_be-linux-gnu -emit-cir %s -o %t.cir
+// RUN: %clang_cc1 -triple aarch64_be-linux-gnu -fclangir -emit-cir %s -o %t.cir
 // RUN: FileCheck --input-file=%t.cir %s --check-prefix=BIG
 
 void foo() {}
diff --git a/clang/test/CIR/CodeGen/module-asm.c b/clang/test/CIR/CodeGen/module-asm.c
index e6cec5e0ee948..049a90f69d393 100644
--- a/clang/test/CIR/CodeGen/module-asm.c
+++ b/clang/test/CIR/CodeGen/module-asm.c
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-cir %s -o %t.cir 
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir 
 // RUN: FileCheck --input-file=%t.cir %s
 
 // CHECK:  cir.module_asm = [".globl bar", ".globl foo"]
diff --git a/clang/test/Driver/cir-flags-error.c b/clang/test/Driver/cir-flags-error.c
new file mode 100644
index 0000000000000..a76e3173fb33c
--- /dev/null
+++ b/clang/test/Driver/cir-flags-error.c
@@ -0,0 +1,11 @@
+// REQUIRES: cir-support
+
+// RUN: not %clang -emit-cir %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=EMIT_CIR_ERROR
+// EMIT_CIR_ERROR: error: -emit-cir is only valid with -fclangir
+
+// RUN: %clang -fclangir -emit-cir %s -o /dev/null 2>&1 | FileCheck %s --allow-empty -check-prefix=EMIT_CIR_OK
+// EMIT_CIR_OK-NOT: error: -emit-cir is only valid with -fclangir
+
+int main(void) {
+  return 0;
+}
diff --git a/clang/test/Driver/cir-input-without-fclangir.cir b/clang/test/Driver/cir-input-without-fclangir.cir
new file mode 100644
index 0000000000000..2c4354511a322
--- /dev/null
+++ b/clang/test/Driver/cir-input-without-fclangir.cir
@@ -0,0 +1,20 @@
+// RUN: not %clang %s -emit-llvm -o /dev/null 2>&1 | FileCheck %s -check-prefix=CIR_INPUT_ERROR
+// CIR_INPUT_ERROR: error: trying to compile CIR module {{.*}} with clang IR disabled; use -fclangir to enable CIR pipeline
+
+// RUN: %clang -fclangir %s -emit-llvm -o /dev/null 2>&1 | FileCheck %s --allow-empty -check-prefix=CIR_INPUT_OK
+// CIR_INPUT_OK-NOT: error: trying to compile CIR module
+
+// REQUIRES: x86-registered-target
+// REQUIRES: cir-support
+
+!s32i = !cir.int<s, 32>
+
+module attributes {cir.lang = #cir.lang<cxx>, cir.triple = "x86_64-unknown-linux-gnu"} {
+  cir.func @test_function() -> !s32i {
+    %0 = cir.alloca !s32i, !cir.ptr<!s32i>, ["__retval"] {alignment = 4 : i64}
+    %1 = cir.const #cir.int<42> : !s32i
+    cir.store %1, %0 : !s32i, !cir.ptr<!s32i>
+    %2 = cir.load %0 : !cir.ptr<!s32i>, !s32i
+    cir.return %2 : !s32i
+  }
+}

andykaylor

I don't understand the use case you're preparing for here. If I have this command line:

clang -emit-cir foo.cpp bar.cir

This will produce an error, saying I can't use -emit-cir without -fclangir, right? What's the case where this is useful?

andykaylor · 2025-11-07T17:02:25Z

clang/lib/Frontend/CompilerInvocation.cpp

+  if (!Args.hasArg(OPT_fclangir) && Args.hasArg(OPT_emit_cir))
+    Diags.Report(diag::err_drv_emit_cir_without_fclangir);
+#else
+  if (Args.hasArg(OPT_emit_cir))


We should also report an error if -fclangir is used in this case. Currently, we silently do nothing.

mmha · 2025-11-07T18:01:42Z

I mostly wondered about the expected behavior in these cases:

clang foo.cpp bar.cir
clang -emit-cir foo.cpp bar.cir
clang -emit-llvm foo.cpp bar.cir

I wouldn't want the presence of a .cir file to implicitly change the pipeline of the other files. But in ExecuteCompilerInvocation.cpp we need to decide whether to enable CIR or not based on all input files. So I was looking for ways to make the enablement of CIR more explicit.

To me -emit-cir means "dump the IR" and not "change the pipeline, then dump the IR". I think it's better to require two separate flags. If no CIR is generated during compilation this shouldn't do anything, just like -emit-ast errors out for LLVM IR files.

This patch isn't necessary for enable CIR as a source lang but note the llvm::report_fatal_error("-emit-cir and only valid when using -fclangir"); line I deleted. This was dead code but the string suggests this was the intended behavior.

mmha requested review from Andres-Salamanca, JustinStitt, andykaylor, bcardosolopes and erichkeane November 7, 2025 10:08

llvmbot added clang Clang issues not falling into any other category clang:driver 'clang' and 'clang++' user-facing binaries. Not 'clang-cl' clang:frontend Language frontend issues, e.g. anything involving "Sema" ClangIR Anything related to the ClangIR project labels Nov 7, 2025

andykaylor reviewed Nov 7, 2025

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[CIR] -emit-cir should not implicitly enable the CIR pipeline #166916

[CIR] -emit-cir should not implicitly enable the CIR pipeline #166916

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mmha commented Nov 7, 2025

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[CIR] -emit-cir should not implicitly enable the CIR pipeline #166916

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[CIR] -emit-cir should not implicitly enable the CIR pipeline #166916

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llvmbot commented Nov 7, 2025 •

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