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return 0 from Run when it doesn't specify a return value (#7180)
https://carbon.compiler-explorer.com/z/88K9Kh5Wo shows the program exiting with a garbage value copied from uninitialized memory. This PR modifies `lower` to detect if the function lowered is the entry point and doesn't specify a return type. If so, it emits different LLVM IR to return int32 0, and modifies the lowered function signature to match the int32 return type.
This commit is contained in:
Lucile Rose Nihlen
@@ -0,0 +1,69 @@
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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/convert.carbon
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//
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// AUTOUPDATE
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// TIP: To test this file alone, run:
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// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/lower/testdata/return/function_ids_in_different_files.carbon
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// TIP: To dump output, run:
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// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/lower/testdata/return/function_ids_in_different_files.carbon
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// --- a.carbon
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library "[[@TEST_NAME]]";
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fn F(unused T:! type) {
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// Explicit no-argument `return` in a generic function.
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return;
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}
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// --- b.carbon
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library "[[@TEST_NAME]]";
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import library "a";
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fn G() {
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// Create specific in a different file.
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F({});
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}
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// CHECK:STDOUT: ; ModuleID = 'a.carbon'
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// CHECK:STDOUT: source_filename = "a.carbon"
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// CHECK:STDOUT:
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// CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
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// CHECK:STDOUT: !llvm.dbg.cu = !{!2}
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// CHECK:STDOUT:
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// CHECK:STDOUT: !0 = !{i32 7, !"Dwarf Version", i32 5}
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// CHECK:STDOUT: !1 = !{i32 2, !"Debug Info Version", i32 3}
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// CHECK:STDOUT: !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
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// CHECK:STDOUT: !3 = !DIFile(filename: "a.carbon", directory: "")
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// CHECK:STDOUT: ; ModuleID = 'b.carbon'
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// CHECK:STDOUT: source_filename = "b.carbon"
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// CHECK:STDOUT:
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// CHECK:STDOUT: ; Function Attrs: nounwind
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// CHECK:STDOUT: define void @_CG.Main() #0 !dbg !4 {
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// CHECK:STDOUT: entry:
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// CHECK:STDOUT: call void @_CF.Main.6944efcfbb6a8360(), !dbg !7
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// CHECK:STDOUT: ret void, !dbg !8
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: ; Function Attrs: nounwind
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// CHECK:STDOUT: define linkonce_odr void @_CF.Main.6944efcfbb6a8360() #0 !dbg !9 {
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// CHECK:STDOUT: ret void, !dbg !11
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: attributes #0 = { nounwind }
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// CHECK:STDOUT:
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// CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
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// CHECK:STDOUT: !llvm.dbg.cu = !{!2}
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// CHECK:STDOUT:
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// CHECK:STDOUT: !0 = !{i32 7, !"Dwarf Version", i32 5}
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// CHECK:STDOUT: !1 = !{i32 2, !"Debug Info Version", i32 3}
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// CHECK:STDOUT: !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
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// CHECK:STDOUT: !3 = !DIFile(filename: "b.carbon", directory: "")
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// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "G", linkageName: "_CG.Main", scope: null, file: !3, line: 3, type: !5, spFlags: DISPFlagDefinition, unit: !2)
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// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
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// CHECK:STDOUT: !6 = !{null}
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// CHECK:STDOUT: !7 = !DILocation(line: 5, column: 3, scope: !4)
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// CHECK:STDOUT: !8 = !DILocation(line: 3, column: 1, scope: !4)
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// CHECK:STDOUT: !9 = distinct !DISubprogram(name: "F", linkageName: "_CF.Main.6944efcfbb6a8360", scope: null, file: !10, line: 2, type: !5, spFlags: DISPFlagDefinition, unit: !2)
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// CHECK:STDOUT: !10 = !DIFile(filename: "a.carbon", directory: "")
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// CHECK:STDOUT: !11 = !DILocation(line: 4, column: 3, scope: !9)
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@@ -0,0 +1,55 @@
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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/convert.carbon
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//
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// AUTOUPDATE
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// TIP: To test this file alone, run:
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// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/lower/testdata/return/no_return_from_run.carbon
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// TIP: To dump output, run:
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// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/lower/testdata/return/no_return_from_run.carbon
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// We expect this to lower to LLVM IR that returns i32 0.
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fn Run() {}
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// LLVM IR for calls to Run should reflect the i32 call type of the lowered Run function.
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fn Foo() {
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Run();
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}
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// CHECK:STDOUT: ; ModuleID = 'no_return_from_run.carbon'
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// CHECK:STDOUT: source_filename = "no_return_from_run.carbon"
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// CHECK:STDOUT:
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// CHECK:STDOUT: ; Function Attrs: nounwind
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// CHECK:STDOUT: define i32 @main() #0 !dbg !4 {
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// CHECK:STDOUT: entry:
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// CHECK:STDOUT: ret i32 0, !dbg !8
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: ; Function Attrs: nounwind
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// CHECK:STDOUT: define void @_CFoo.Main() #0 !dbg !9 {
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// CHECK:STDOUT: entry:
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// CHECK:STDOUT: %Run.call = call i32 @main(), !dbg !12
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// CHECK:STDOUT: ret void, !dbg !13
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: attributes #0 = { nounwind }
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// CHECK:STDOUT:
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// CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
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// CHECK:STDOUT: !llvm.dbg.cu = !{!2}
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// CHECK:STDOUT:
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// CHECK:STDOUT: !0 = !{i32 7, !"Dwarf Version", i32 5}
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// CHECK:STDOUT: !1 = !{i32 2, !"Debug Info Version", i32 3}
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// CHECK:STDOUT: !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
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// CHECK:STDOUT: !3 = !DIFile(filename: "no_return_from_run.carbon", directory: "")
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// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "Run", linkageName: "main", scope: null, file: !3, line: 14, type: !5, spFlags: DISPFlagDefinition, unit: !2)
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// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
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// CHECK:STDOUT: !6 = !{!7}
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// CHECK:STDOUT: !7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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// CHECK:STDOUT: !8 = !DILocation(line: 14, column: 1, scope: !4)
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// CHECK:STDOUT: !9 = distinct !DISubprogram(name: "Foo", linkageName: "_CFoo.Main", scope: null, file: !3, line: 17, type: !10, spFlags: DISPFlagDefinition, unit: !2)
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// CHECK:STDOUT: !10 = !DISubroutineType(types: !11)
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// CHECK:STDOUT: !11 = !{null}
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// CHECK:STDOUT: !12 = !DILocation(line: 18, column: 3, scope: !9)
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// CHECK:STDOUT: !13 = !DILocation(line: 17, column: 1, scope: !9)
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