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Mirror of https://github.com/RPCS3/llvm-mirror
c6275bc0ce
CodeExtractor handles bitcasts in the extracted region that have
lifetime markers users in the outer region as outputs. That
creates unnecessary alloca/reload instructions and extra lifetime
markers. The patch identifies those cases, and replaces uses in
out-of-region lifetime markers with new bitcasts in the outer region.
**Example**
```
define void @foo() {
entry:
%0 = alloca i32
br label %extract
extract:
%1 = bitcast i32* %0 to i8*
call void @llvm.lifetime.start.p0i8(i64 4, i8* %1)
call void @use(i32* %0)
br label %exit
exit:
call void @use(i32* %0)
call void @llvm.lifetime.end.p0i8(i64 4, i8* %1)
ret void
}
```
**Current extraction**
```
define void @foo() {
entry:
%.loc = alloca i8*, align 8
%0 = alloca i32, align 4
br label %codeRepl
codeRepl: ; preds = %entry
%lt.cast = bitcast i8** %.loc to i8*
call void @llvm.lifetime.start.p0i8(i64 -1, i8* %lt.cast)
%lt.cast1 = bitcast i32* %0 to i8*
call void @llvm.lifetime.start.p0i8(i64 -1, i8* %lt.cast1)
call void @foo.extract(i32* %0, i8** %.loc)
%.reload = load i8*, i8** %.loc, align 8
call void @llvm.lifetime.end.p0i8(i64 -1, i8* %lt.cast)
br label %exit
exit: ; preds = %codeRepl
call void @use(i32* %0)
call void @llvm.lifetime.end.p0i8(i64 4, i8* %.reload)
ret void
}
define internal void @foo.extract(i32* %0, i8** %.out) {
newFuncRoot:
br label %extract
exit.exitStub: ; preds = %extract
ret void
extract: ; preds = %newFuncRoot
%1 = bitcast i32* %0 to i8*
store i8* %1, i8** %.out, align 8
call void @use(i32* %0)
br label %exit.exitStub
}
```
**Extraction with patch**
```
define void @foo() {
entry:
%0 = alloca i32, align 4
br label %codeRepl
codeRepl: ; preds = %entry
%lt.cast1 = bitcast i32* %0 to i8*
call void @llvm.lifetime.start.p0i8(i64 -1, i8* %lt.cast1)
call void @foo.extract(i32* %0)
br label %exit
exit: ; preds = %codeRepl
call void @use(i32* %0)
%lt.cast = bitcast i32* %0 to i8*
call void @llvm.lifetime.end.p0i8(i64 4, i8* %lt.cast)
ret void
}
define internal void @foo.extract(i32* %0) {
newFuncRoot:
br label %extract
exit.exitStub: ; preds = %extract
ret void
extract: ; preds = %newFuncRoot
%1 = bitcast i32* %0 to i8*
call void @use(i32* %0)
br label %exit.exitStub
}
```
Reviewed By: vsk
Differential Revision: https://reviews.llvm.org/D90689
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The LLVM Compiler Infrastructure ================================ This directory and its subdirectories contain source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and runtime environments. LLVM is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt. Please see the documentation provided in docs/ for further assistance with LLVM, and in particular docs/GettingStarted.rst for getting started with LLVM and docs/README.txt for an overview of LLVM's documentation setup. If you are writing a package for LLVM, see docs/Packaging.rst for our suggestions.