mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 22:02:23 +01:00
Richard Smith
c04d62a7d1
Non-entry-block allocas will allocate new stack memory each time they're reached, resulting in leaking stack memory over time for allocas in a loop. Move all such allocas to the entry block instead, and use an LLVM intrinsic to mark when the lifetime of the variable actually begins.
66 lines
3.6 KiB
Plaintext
66 lines
3.6 KiB
Plaintext
// 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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// 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/pointer/pointer_to_pointer.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/pointer/pointer_to_pointer.carbon
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fn F(p: i32**) -> i32 {
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var a: i32** = p;
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var b: i32* = *p;
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var c: i32** = &b;
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return **c;
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}
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// CHECK:STDOUT: ; ModuleID = 'pointer_to_pointer.carbon'
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// CHECK:STDOUT: source_filename = "pointer_to_pointer.carbon"
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// CHECK:STDOUT:
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// CHECK:STDOUT: define i32 @_CF.Main(ptr %p) !dbg !4 {
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// CHECK:STDOUT: entry:
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// CHECK:STDOUT: %a.var = alloca ptr, align 8, !dbg !7
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// CHECK:STDOUT: %b.var = alloca ptr, align 8, !dbg !7
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// CHECK:STDOUT: %c.var = alloca ptr, align 8, !dbg !7
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// CHECK:STDOUT: call void @llvm.lifetime.start.p0(i64 8, ptr %a.var), !dbg !7
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// CHECK:STDOUT: store ptr %p, ptr %a.var, align 8, !dbg !8
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// CHECK:STDOUT: call void @llvm.lifetime.start.p0(i64 8, ptr %b.var), !dbg !7
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// CHECK:STDOUT: %.loc13_17.2 = load ptr, ptr %p, align 8, !dbg !9
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// CHECK:STDOUT: store ptr %.loc13_17.2, ptr %b.var, align 8, !dbg !10
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// CHECK:STDOUT: call void @llvm.lifetime.start.p0(i64 8, ptr %c.var), !dbg !7
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// CHECK:STDOUT: store ptr %b.var, ptr %c.var, align 8, !dbg !11
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// CHECK:STDOUT: %.loc15_12 = load ptr, ptr %c.var, align 8, !dbg !12
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// CHECK:STDOUT: %.loc15_11.2 = load ptr, ptr %.loc15_12, align 8, !dbg !13
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// CHECK:STDOUT: %.loc15_10.2 = load i32, ptr %.loc15_11.2, align 4, !dbg !14
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// CHECK:STDOUT: ret i32 %.loc15_10.2, !dbg !15
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
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// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #0
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// CHECK:STDOUT:
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// CHECK:STDOUT: ; uselistorder directives
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// CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 2, 1, 0 }
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// CHECK:STDOUT:
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// CHECK:STDOUT: attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
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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, file: !3, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
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// CHECK:STDOUT: !3 = !DIFile(filename: "pointer_to_pointer.carbon", directory: "")
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// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "F", linkageName: "_CF.Main", scope: null, file: !3, line: 11, type: !5, spFlags: DISPFlagDefinition, unit: !2)
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// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
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// CHECK:STDOUT: !6 = !{}
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// CHECK:STDOUT: !7 = !DILocation(line: 12, column: 7, scope: !4)
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// CHECK:STDOUT: !8 = !DILocation(line: 12, column: 3, scope: !4)
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// CHECK:STDOUT: !9 = !DILocation(line: 13, column: 17, scope: !4)
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// CHECK:STDOUT: !10 = !DILocation(line: 13, column: 3, scope: !4)
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// CHECK:STDOUT: !11 = !DILocation(line: 14, column: 3, scope: !4)
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// CHECK:STDOUT: !12 = !DILocation(line: 15, column: 12, scope: !4)
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// CHECK:STDOUT: !13 = !DILocation(line: 15, column: 11, scope: !4)
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// CHECK:STDOUT: !14 = !DILocation(line: 15, column: 10, scope: !4)
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// CHECK:STDOUT: !15 = !DILocation(line: 15, column: 3, scope: !4)
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