3b4e79398d
This patch introduces support for Integrated Distributed ThinLTO (DTLTO) in ELF LLD. DTLTO enables the distribution of ThinLTO backend compilations via external distribution systems, such as Incredibuild, during the traditional link step: https://llvm.org/docs/DTLTO.html. It is expected that users will invoke DTLTO through the compiler driver (e.g., Clang) rather than calling LLD directly. A Clang-side interface for DTLTO will be added in a follow-up patch. Note: Bitcode members of archives (thin or non-thin) are not currently supported. This will be addressed in a future change. As a consequence of this lack of support, this patch is not sufficient to allow for self-hosting an LLVM build with DTLTO. Theoretically, --start-lib/--end-lib could be used instead of archives in a self-host build. However, it's unclear how --start-lib/--end-lib can be easily used with the LLVM build system. Testing: - ELF LLD `lit` test coverage has been added, using a mock distributor to avoid requiring Clang. - Cross-project `lit` tests cover integration with Clang. For the design discussion of the DTLTO feature, see: #126654.
42 lines
1.2 KiB
C
42 lines
1.2 KiB
C
// REQUIRES: ld.lld
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/// Simple test that DTLTO works with a single input bitcode file and that
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/// --save-temps can be applied to the remote compilation.
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// RUN: rm -rf %t && mkdir %t && cd %t
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// RUN: %clang --target=x86_64-linux-gnu -c -flto=thin %s -o dtlto.o
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// RUN: ld.lld dtlto.o \
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// RUN: --thinlto-distributor=%python \
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// RUN: --thinlto-distributor-arg=%llvm_src_root/utils/dtlto/local.py \
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// RUN: --thinlto-remote-compiler=%clang \
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// RUN: --thinlto-remote-compiler-arg=--save-temps
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/// Check that the required output files have been created.
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// RUN: ls | sort | FileCheck %s
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/// No files are expected before.
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// CHECK-NOT: {{.}}
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/// Linked ELF.
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// CHECK: {{^}}a.out{{$}}
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/// Produced by the bitcode compilation.
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// CHECK-NEXT: {{^}}dtlto.o{{$}}
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/// --save-temps output for the backend compilation.
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// CHECK-NEXT: {{^}}dtlto.s{{$}}
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// CHECK-NEXT: {{^}}dtlto.s.0.preopt.bc{{$}}
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// CHECK-NEXT: {{^}}dtlto.s.1.promote.bc{{$}}
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// CHECK-NEXT: {{^}}dtlto.s.2.internalize.bc{{$}}
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// CHECK-NEXT: {{^}}dtlto.s.3.import.bc{{$}}
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// CHECK-NEXT: {{^}}dtlto.s.4.opt.bc{{$}}
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// CHECK-NEXT: {{^}}dtlto.s.5.precodegen.bc{{$}}
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// CHECK-NEXT: {{^}}dtlto.s.resolution.txt{{$}}
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/// No files are expected after.
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// CHECK-NOT: {{.}}
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int _start() { return 0; }
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