forked from OSchip/llvm-project
9a6c0bdcbd
Summary:
Loop idiom recognize tries to convert loops like
```
int foo(int x) {
int cnt = 0;
while (x) {
x >>= 1;
++cnt;
}
return cnt;
}
```
into calls to ctlz, but if x is initially negative this loop should be infinite.
It happens that the cases that motivated this change have an absolute value of x before the loop. So this patch restricts the transform to cases where we know x is positive. Note: We are relying on the absolute value of INT_MIN to be undefined so we can assume that the result is always positive.
Fixes PR37479
Reviewers: spatel, hfinkel, efriedma, javed.absar
Reviewed By: efriedma
Subscribers: dmgreen, llvm-commits
Differential Revision: https://reviews.llvm.org/D47348
llvm-svn: 333702
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| .. | ||
| Analysis | ||
| Assembler | ||
| Bindings | ||
| Bitcode | ||
| BugPoint | ||
| CodeGen | ||
| DebugInfo | ||
| Examples | ||
| ExecutionEngine | ||
| Feature | ||
| FileCheck | ||
| Instrumentation | ||
| Integer | ||
| JitListener | ||
| LTO | ||
| Linker | ||
| MC | ||
| Object | ||
| ObjectYAML | ||
| Other | ||
| SafepointIRVerifier | ||
| SymbolRewriter | ||
| TableGen | ||
| ThinLTO/X86 | ||
| Transforms | ||
| Unit | ||
| Verifier | ||
| YAMLParser | ||
| tools | ||
| .clang-format | ||
| CMakeLists.txt | ||
| TestRunner.sh | ||
| lit.cfg.py | ||
| lit.site.cfg.py.in | ||