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| author | Richard Biener <rguenther@suse.de> | 2024-03-04 10:38:31 +0100 |
|---|---|---|
| committer | Richard Biener <rguenther@suse.de> | 2024-03-04 11:44:54 +0100 |
| commit | cde50296a19b109909089b91d532d2c8455f5f10 (patch) | |
| tree | 1e917627fa5126700eeddd051c83d2a484ecda29 | |
| parent | 324d2907c86f05e40dc52d226940308f53a956c2 (diff) | |
| download | gcc-cde50296a19b109909089b91d532d2c8455f5f10.zip gcc-cde50296a19b109909089b91d532d2c8455f5f10.tar.gz gcc-cde50296a19b109909089b91d532d2c8455f5f10.tar.bz2 | |
tree-optimization/114203 - wrong CLZ niter computation
For precision less than int we apply the adjustment to make it defined
at zero after the adjustment to make it compute CLZ rather than CTZ.
That's wrong.
PR tree-optimization/114203
* tree-ssa-loop-niter.cc (build_cltz_expr): Apply CTZ->CLZ
adjustment before making the result defined at zero.
* gcc.dg/torture/pr114203.c: New testcase.
| -rw-r--r-- | gcc/testsuite/gcc.dg/torture/pr114203.c | 21 | ||||
| -rw-r--r-- | gcc/tree-ssa-loop-niter.cc | 7 |
2 files changed, 24 insertions, 4 deletions
diff --git a/gcc/testsuite/gcc.dg/torture/pr114203.c b/gcc/testsuite/gcc.dg/torture/pr114203.c new file mode 100644 index 0000000..0ef6279 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr114203.c @@ -0,0 +1,21 @@ +/* { dg-do run } */ + +int __attribute__((noipa)) +foo (unsigned char b) +{ + int c = 0; + + while (b) { + b >>= 1; + c++; + } + + return c; +} + +int main() +{ + if (foo(0) != 0) + __builtin_abort (); + return 0; +} diff --git a/gcc/tree-ssa-loop-niter.cc b/gcc/tree-ssa-loop-niter.cc index 038e433..c6d010f 100644 --- a/gcc/tree-ssa-loop-niter.cc +++ b/gcc/tree-ssa-loop-niter.cc @@ -2288,6 +2288,9 @@ build_cltz_expr (tree src, bool leading, bool define_at_zero) src = fold_convert (unsigned_type_node, src); call = build_call_expr (fn, 1, src); + if (leading && prec < i_prec) + call = fold_build2 (MINUS_EXPR, integer_type_node, call, + build_int_cst (integer_type_node, i_prec - prec)); if (define_at_zero) { tree is_zero = fold_build2 (NE_EXPR, boolean_type_node, src, @@ -2295,10 +2298,6 @@ build_cltz_expr (tree src, bool leading, bool define_at_zero) call = fold_build3 (COND_EXPR, integer_type_node, is_zero, call, build_int_cst (integer_type_node, prec)); } - - if (leading && prec < i_prec) - call = fold_build2 (MINUS_EXPR, integer_type_node, call, - build_int_cst (integer_type_node, i_prec - prec)); } return call; |