diff --git a/toolchain/lower/file_context.cpp b/toolchain/lower/file_context.cpp index 2426133dd841..5e6ca02b23a5 100644 --- a/toolchain/lower/file_context.cpp +++ b/toolchain/lower/file_context.cpp @@ -460,7 +460,7 @@ auto FileContext::GetOrCreateLLVMFunction( // file. That's OK. // TODO: If the prior function was inexact and the new one is not, we should // lower this new one and replace the existing function with it. - // TODO: Check-fail or maybe diagnose if the two LLVM functions are not + // TODO: CHECK-fail or maybe diagnose if the two LLVM functions are not // produced by declarations of the same Carbon function. Name collisions // between non-private members of the same library should have been // diagnosed by check if detected, but it's not clear that check will @@ -883,6 +883,19 @@ auto FileContext::BuildNonCppGlobalVariableDecl(SemIR::VarStorage var_storage) ("var.anon" + inst_namer_->GetUnscopedNameFor(var_storage.pattern_id)) .str(); } + } else if (auto* existing = llvm_module().getNamedGlobal(mangled_name)) { + // We might have already declared this variable while lowering a different + // file, such as when lowering a specific of a generic function from the + // file that defines the variable. Reuse that declaration rather than + // creating a new one, which LLVM would rename to avoid the collision. + // + // TODO: CHECK-fail or maybe diagnose if the two LLVM variables are not + // produced by declarations of the same Carbon variable. Name collisions + // between non-private members of the same library should have been + // diagnosed by check if detected, but it's not clear that check will + // always be able to see this problem. In theory, name collisions could + // also occur due to fingerprint collision. + return existing; } auto* type = GetType(var_storage.type_id); diff --git a/toolchain/lower/testdata/var/import.carbon b/toolchain/lower/testdata/var/import.carbon index 8f9f8b5da0a1..e0fae696f01d 100644 --- a/toolchain/lower/testdata/var/import.carbon +++ b/toolchain/lower/testdata/var/import.carbon @@ -158,9 +158,6 @@ fn Z() -> i32 { return z; } // CHECK:STDOUT: @_Cv.Main = external global { i32, i32 } // CHECK:STDOUT: @_Cy.Main = external global i32 // CHECK:STDOUT: @_Cz.Main = external global { i32, i32 } -// CHECK:STDOUT: @_Cv.Main.1 = external global { i32, i32 } -// CHECK:STDOUT: @_Cy.Main.2 = external global i32 -// CHECK:STDOUT: @_Cz.Main.3 = external global { i32, i32 } // CHECK:STDOUT: @_Cx.Main = external global i32 // CHECK:STDOUT: // CHECK:STDOUT: ; Function Attrs: nounwind diff --git a/toolchain/lower/testdata/var/import_from_generic.carbon b/toolchain/lower/testdata/var/import_from_generic.carbon new file mode 100644 index 000000000000..5ef17d273af4 --- /dev/null +++ b/toolchain/lower/testdata/var/import_from_generic.carbon @@ -0,0 +1,109 @@ +// Part of the Carbon Language project, under the Apache License v2.0 with LLVM +// Exceptions. See /LICENSE for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/int.carbon +// +// AUTOUPDATE +// TIP: To test this file alone, run: +// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/lower/testdata/var/import_from_generic.carbon +// TIP: To dump output, run: +// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/lower/testdata/var/import_from_generic.carbon + +// --- lib.carbon + +library "[[@TEST_NAME]]"; + +var g: i32 = 1; + +fn Get[T: type](_: T) -> i32 { return g; } + +// --- use.carbon + +library "[[@TEST_NAME]]"; + +import library "lib"; + +// The direct reference to `g` and the reference from the specific `Get(())` +// should both refer to the same global. +fn F() -> i32 { return g; } +fn G() -> i32 { return Get(()); } + +// CHECK:STDOUT: ; --- +// CHECK:STDOUT: ; ModuleID = 'lib.carbon' +// CHECK:STDOUT: source_filename = "lib.carbon" +// CHECK:STDOUT: +// CHECK:STDOUT: @_Cg.Main = global i32 0 +// CHECK:STDOUT: @llvm.global_ctors = appending global [1 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 0, ptr @_C__global_init.Main, ptr null }] +// CHECK:STDOUT: +// CHECK:STDOUT: ; Function Attrs: nounwind +// CHECK:STDOUT: define internal void @_C__global_init.Main() #0 !dbg !23 { +// CHECK:STDOUT: entry: +// CHECK:STDOUT: store i32 1, ptr @_Cg.Main, align 4, !dbg !24 +// CHECK:STDOUT: ret void, !dbg !25 +// CHECK:STDOUT: } +// CHECK:STDOUT: +// CHECK:STDOUT: attributes #0 = { nounwind } +// CHECK:STDOUT: +// CHECK:STDOUT: !llvm.dbg.cu = !{!19} +// CHECK:STDOUT: !llvm.module.flags = !{!2, !3} +// CHECK:STDOUT: +// CHECK:STDOUT: !2 = !{i32 7, !"Dwarf Version", i32 5} +// CHECK:STDOUT: !3 = !{i32 2, !"Debug Info Version", i32 3} +// CHECK:STDOUT: !18 = !DIFile(filename: "lib.carbon", directory: "") +// CHECK:STDOUT: !19 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !18, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug) +// CHECK:STDOUT: !21 = !{null} +// CHECK:STDOUT: !22 = !DISubroutineType(types: !21) +// CHECK:STDOUT: !23 = distinct !DISubprogram(name: "__global_init", linkageName: "_C__global_init.Main", scope: null, file: !18, type: !22, spFlags: DISPFlagDefinition, unit: !19) +// CHECK:STDOUT: !24 = !DILocation(line: 4, column: 1, scope: !23) +// CHECK:STDOUT: !25 = !DILocation(line: 0, scope: !23) +// CHECK:STDOUT: +// CHECK:STDOUT: ; --- +// CHECK:STDOUT: ; ModuleID = 'use.carbon' +// CHECK:STDOUT: source_filename = "use.carbon" +// CHECK:STDOUT: +// CHECK:STDOUT: @_Cg.Main = external global i32 +// CHECK:STDOUT: +// CHECK:STDOUT: ; Function Attrs: nounwind +// CHECK:STDOUT: define i32 @_CF.Main() #0 !dbg !30 { +// CHECK:STDOUT: entry: +// CHECK:STDOUT: %.loc8_24 = load i32, ptr @_Cg.Main, align 4, !dbg !33 +// CHECK:STDOUT: ret i32 %.loc8_24, !dbg !34 +// CHECK:STDOUT: } +// CHECK:STDOUT: +// CHECK:STDOUT: ; Function Attrs: nounwind +// CHECK:STDOUT: define i32 @_CG.Main() #0 !dbg !35 { +// CHECK:STDOUT: entry: +// CHECK:STDOUT: %Get.call = call i32 @_CGet.Main.e43630e9a6c38c3f(), !dbg !38 +// CHECK:STDOUT: ret i32 %Get.call, !dbg !39 +// CHECK:STDOUT: } +// CHECK:STDOUT: +// CHECK:STDOUT: ; Function Attrs: nounwind +// CHECK:STDOUT: define linkonce_odr i32 @_CGet.Main.e43630e9a6c38c3f() #0 !dbg !40 { +// CHECK:STDOUT: %1 = load i32, ptr @_Cg.Main, align 4, !dbg !44 +// CHECK:STDOUT: ret i32 %1, !dbg !45 +// CHECK:STDOUT: } +// CHECK:STDOUT: +// CHECK:STDOUT: attributes #0 = { nounwind } +// CHECK:STDOUT: +// CHECK:STDOUT: !llvm.dbg.cu = !{!27} +// CHECK:STDOUT: !llvm.module.flags = !{!2, !3} +// CHECK:STDOUT: +// CHECK:STDOUT: !2 = !{i32 7, !"Dwarf Version", i32 5} +// CHECK:STDOUT: !3 = !{i32 2, !"Debug Info Version", i32 3} +// CHECK:STDOUT: !18 = !DIFile(filename: "lib.carbon", directory: "") +// CHECK:STDOUT: !20 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) +// CHECK:STDOUT: !26 = !DIFile(filename: "use.carbon", directory: "") +// CHECK:STDOUT: !27 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !26, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug) +// CHECK:STDOUT: !28 = !{!20} +// CHECK:STDOUT: !29 = !DISubroutineType(types: !28) +// CHECK:STDOUT: !30 = distinct !DISubprogram(name: "F", linkageName: "_CF.Main", scope: null, file: !26, line: 8, type: !29, spFlags: DISPFlagDefinition, unit: !27) +// CHECK:STDOUT: !33 = !DILocation(line: 8, column: 24, scope: !30) +// CHECK:STDOUT: !34 = !DILocation(line: 8, column: 17, scope: !30) +// CHECK:STDOUT: !35 = distinct !DISubprogram(name: "G", linkageName: "_CG.Main", scope: null, file: !26, line: 9, type: !29, spFlags: DISPFlagDefinition, unit: !27) +// CHECK:STDOUT: !38 = !DILocation(line: 9, column: 24, scope: !35) +// CHECK:STDOUT: !39 = !DILocation(line: 9, column: 17, scope: !35) +// CHECK:STDOUT: !40 = distinct !DISubprogram(name: "Get", linkageName: "_CGet.Main.e43630e9a6c38c3f", scope: null, file: !18, line: 6, type: !29, spFlags: DISPFlagDefinition, unit: !27) +// CHECK:STDOUT: !44 = !DILocation(line: 6, column: 39, scope: !40) +// CHECK:STDOUT: !45 = !DILocation(line: 6, column: 32, scope: !40) +// CHECK:STDOUT: