0f52545289
This commit introduces support for outlining functions across modules
using codegen data generated from previous codegen. The codegen data
currently manages the outlined hash tree, which records outlining
instances that occurred locally in the past.
The machine outliner now operates in one of three modes:
1. CGDataMode::None: This is the default outliner mode that uses the
suffix tree to identify (local) outlining candidates within a module.
This mode is also used by (full)LTO to maintain optimal behavior with
the combined module.
2. CGDataMode::Write (`-codegen-data-generate`): This mode is identical
to the default mode, but it also publishes the stable hash sequences of
instructions in the outlined functions into a local outlined hash tree.
It then encodes this into the `__llvm_outline` section, which will be
dead-stripped at link time.
3. CGDataMode::Read (`-codegen-data-use-path={.cgdata}`): This mode
reads a codegen data file (.cgdata) and initializes a global outlined
hash tree. This tree is used to generate global outlining candidates.
Note that the codegen data file has been post-processed with the raw
`__llvm_outline` sections from all native objects using the
`llvm-cgdata` tool (or a linker, `LLD`, or a new ThinLTO pipeline
later).
This depends on https://github.com/llvm/llvm-project/pull/105398. After
this PR, LLD (https://github.com/llvm/llvm-project/pull/90166) and Clang
(https://github.com/llvm/llvm-project/pull/90304) will follow for each
client side support.
This is a patch for
https://discourse.llvm.org/t/rfc-enhanced-machine-outliner-part-2-thinlto-nolto/78753.
41 lines
1.5 KiB
LLVM
41 lines
1.5 KiB
LLVM
; This test verifies the stable hash values for different global variables
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; that have distinct names.
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; We generate two different cgdata files from nearly identical outline instances,
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; with the only difference being the last call target globals, @g vs @h.
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; RUN: split-file %s %t
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; RUN: llc -mtriple=arm64-apple-darwin -enable-machine-outliner -codegen-data-generate=true -filetype=obj %t/local-g.ll -o %t/local-g.o
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; RUN: llvm-cgdata --merge %t/local-g.o -o %t/local-g.cgdata
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; RUN: llvm-cgdata --convert %t/local-g.cgdata -o %t/local-g.cgtext
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; RUN: llc -mtriple=arm64-apple-darwin -enable-machine-outliner -codegen-data-generate=true -filetype=obj %t/local-h.ll -o %t/local-h.o
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; RUN: llvm-cgdata --merge %t/local-h.o -o %t/local-h.cgdata
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; RUN: llvm-cgdata --convert %t/local-h.cgdata -o %t/local-h.cgtext
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; We compare the trees which are only different at the terminal node's hash value.
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; Here we simply count the different lines that have `Hash` string.
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; RUN: not diff %t/local-g.cgtext %t/local-h.cgtext 2>&1 | grep Hash | wc -l | FileCheck %s
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; CHECK: 2
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;--- local-g.ll
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declare i32 @g(i32, i32, i32)
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define i32 @f1() minsize {
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%1 = call i32 @g(i32 10, i32 1, i32 2);
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ret i32 %1
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}
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define i32 @f2() minsize {
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%1 = call i32 @g(i32 20, i32 1, i32 2);
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ret i32 %1
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}
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;--- local-h.ll
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declare i32 @h(i32, i32, i32)
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define i32 @f1() minsize {
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%1 = call i32 @h(i32 10, i32 1, i32 2);
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ret i32 %1
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}
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define i32 @f2() minsize {
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%1 = call i32 @h(i32 20, i32 1, i32 2);
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ret i32 %1
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}
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