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
57 lines
1.4 KiB
LLVM
57 lines
1.4 KiB
LLVM
; Check the basic block sections labels option
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; RUN: llc < %s -mtriple=x86_64 -function-sections -basic-block-sections=labels | FileCheck %s
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define void @_Z3bazb(i1 zeroext) personality i32 (...)* @__gxx_personality_v0 {
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br i1 %0, label %2, label %7
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2:
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%3 = invoke i32 @_Z3barv()
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to label %7 unwind label %5
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br label %9
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5:
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landingpad { i8*, i32 }
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catch i8* null
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br label %9
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7:
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%8 = call i32 @_Z3foov()
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br label %9
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9:
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ret void
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}
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declare i32 @_Z3barv() #1
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declare i32 @_Z3foov() #1
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declare i32 @__gxx_personality_v0(...)
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; CHECK-LABEL: _Z3bazb:
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; CHECK-LABEL: .Lfunc_begin0:
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; CHECK-LABEL: .LBB_END0_0:
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; CHECK-LABEL: .LBB0_1:
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; CHECK-LABEL: .LBB_END0_1:
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; CHECK-LABEL: .LBB0_2:
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; CHECK-LABEL: .LBB_END0_2:
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; CHECK-LABEL: .LBB0_3:
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; CHECK-LABEL: .LBB_END0_3:
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; CHECK-LABEL: .Lfunc_end0:
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; CHECK: .section .bb_addr_map,"o",@progbits,.text
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; CHECK-NEXT: .quad .Lfunc_begin0
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; CHECK-NEXT: .byte 4
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; CHECK-NEXT: .uleb128 .Lfunc_begin0-.Lfunc_begin0
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; CHECK-NEXT: .uleb128 .LBB_END0_0-.Lfunc_begin0
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; CHECK-NEXT: .byte 0
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; CHECK-NEXT: .uleb128 .LBB0_1-.Lfunc_begin0
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; CHECK-NEXT: .uleb128 .LBB_END0_1-.LBB0_1
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; CHECK-NEXT: .byte 0
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; CHECK-NEXT: .uleb128 .LBB0_2-.Lfunc_begin0
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; CHECK-NEXT: .uleb128 .LBB_END0_2-.LBB0_2
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; CHECK-NEXT: .byte 1
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; CHECK-NEXT: .uleb128 .LBB0_3-.Lfunc_begin0
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; CHECK-NEXT: .uleb128 .LBB_END0_3-.LBB0_3
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; CHECK-NEXT: .byte 5
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