forked from OSchip/llvm-project
ed6acde8cf
This commit suppresses turning loops like this into "(bitwidth - ctlz(input))".
unsigned foo(unsigned input) {
unsigned num = 0;
do {
++num;
input >>= 1;
} while (input != 0);
return num;
}
The loop version returns a value of 1 for both an input of 0 and an input of 1. Converting to a naive ctlz does not preserve that.
Theoretically we could do better if we checked isKnownNonZero or we could insert a select to handle the divergence. But until we have motivating cases for that, this is the easiest solution.
llvm-svn: 336864
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| .. | ||
| AMDGPU | ||
| ARM | ||
| X86 | ||
| basic-address-space.ll | ||
| basic.ll | ||
| crash.ll | ||
| ctpop-multiple-users-crash.ll | ||
| debug-line.ll | ||
| int_sideeffect.ll | ||
| lir-heurs-multi-block-loop.ll | ||
| memset_noidiom.ll | ||
| non-canonical-loop.ll | ||
| non-integral-pointers.ll | ||
| nontemporal_store.ll | ||
| pr28196.ll | ||
| pr33114.ll | ||
| scev-invalidation.ll | ||
| struct-custom-dl.ll | ||
| struct.ll | ||
| struct_pattern.ll | ||
| unordered-atomic-memcpy-noarch.ll | ||
| unroll-custom-dl.ll | ||
| unroll.ll | ||
| unsafe.ll | ||
| unwind.ll | ||