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bc071d3a95
Further improve the ctz recognition: Avoid ICEing on negative shift
counts or multiply constants. Check the type is a char type for the
string constant case to avoid accidentally matching a wide STRING_CST.
Add a tree_expr_nonzero_p check to allow the optimization even if
CTZ_DEFINED_VALUE_AT_ZERO returns 0 or 1. Add extra test cases.
Bootstrap OK on AArch64 and x64.
gcc/
PR tree-optimization/93231
* tree-ssa-forwprop.c (optimize_count_trailing_zeroes): Check
input_type is unsigned. Use tree_to_shwi for shift constant.
Check CST_STRING element size is CHAR_TYPE_SIZE bits.
(simplify_count_trailing_zeroes): Add test to handle known non-zero
inputs more efficiently.
testsuite/
PR tree-optimization/93231
* gcc.dg/pr90838.c: New test.
* gcc.dg/pr93231.c: New test.
* gcc.target/aarch64/pr90838.c: Use #define u 0.
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