7841e21c98
This patch introduces the new .bb_addr_map section feature which allows us to emit the bits needed for mapping binary profiles to basic blocks into a separate section. The format of the emitted data is represented as follows. It includes a header for every function: | Address of the function | -> 8 bytes (pointer size) | Number of basic blocks in this function (>0) | -> ULEB128 The header is followed by a BB record for every basic block. These records are ordered in the same order as MachineBasicBlocks are placed in the function. Each BB Info is structured as follows: | Offset of the basic block relative to function begin | -> ULEB128 | Binary size of the basic block | -> ULEB128 | BB metadata | -> ULEB128 [ MBB.isReturn() OR MBB.hasTailCall() << 1 OR MBB.isEHPad() << 2 ] The new feature will replace the existing "BB labels" functionality with -basic-block-sections=labels. The .bb_addr_map section scrubs the specially-encoded BB symbols from the binary and makes it friendly to profilers and debuggers. Furthermore, the new feature reduces the binary size overhead from 70% bloat to only 12%. For more information and results please refer to the RFC: https://lists.llvm.org/pipermail/llvm-dev/2020-July/143512.html Reviewed By: MaskRay, snehasish Differential Revision: https://reviews.llvm.org/D85408
41 lines
1.4 KiB
C
41 lines
1.4 KiB
C
// REQUIRES: x86-registered-target
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// RUN: %clang_cc1 -triple x86_64 -S -o - < %s | FileCheck %s --check-prefix=PLAIN
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// RUN: %clang_cc1 -triple x86_64 -S -fbasic-block-sections=all -fbasic-block-sections=none -o - < %s | FileCheck %s --check-prefix=PLAIN
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// RUN: %clang_cc1 -triple x86_64 -S -fbasic-block-sections=all -o - < %s | FileCheck %s --check-prefix=BB_WORLD --check-prefix=BB_ALL
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// RUN: %clang_cc1 -triple x86_64 -S -fbasic-block-sections=list=%S/Inputs/basic-block-sections.funcnames -o - < %s | FileCheck %s --check-prefix=BB_WORLD --check-prefix=BB_LIST
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// RUN: %clang_cc1 -triple x86_64 -S -fbasic-block-sections=all -funique-basic-block-section-names -o - < %s | FileCheck %s --check-prefix=UNIQUE
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int world(int a) {
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if (a > 10)
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return 10;
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else if (a > 5)
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return 5;
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else
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return 0;
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}
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int another(int a) {
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if (a > 10)
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return 20;
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return 0;
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}
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// PLAIN-NOT: section
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// PLAIN: world:
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//
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// BB_WORLD: .section .text.world,"ax",@progbits{{$}}
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// BB_WORLD: world:
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// BB_WORLD: .section .text.world,"ax",@progbits,unique
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// BB_WORLD: world.1:
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// BB_WORLD: .section .text.another,"ax",@progbits
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// BB_ALL: .section .text.another,"ax",@progbits,unique
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// BB_ALL: another.1:
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// BB_LIST-NOT: .section .text.another,"ax",@progbits,unique
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// BB_LIST: another:
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// BB_LIST-NOT: another.1:
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//
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// UNIQUE: .section .text.world.world.1,
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// UNIQUE: .section .text.another.another.1,
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