On 8/4/2026 3:58 AM, [email protected] wrote:
From: Kyrylo Tkachov <[email protected]> The rule folding (type) minmax ((wide_type) a, (wide_type) b) to minmax (a, b) is restricted to scalars. Extension is monotone, so it commutes with the comparison and the outer truncation is exact, and the argument is lanewise, so it holds for vectors unchanged. The vector case additionally needs the narrow operation to be available, otherwise vector lowering would scalarise what used to be a single wide instruction. typedef int v2si __attribute__((vector_size (8))); typedef long v2di __attribute__((vector_size (16))); v2si h (v2si a, v2si b) { v2di x = __builtin_convertvector (a, v2di); v2di y = __builtin_convertvector (b, v2di); return __builtin_convertvector (x < y ? x : y, v2si); } aarch64 -O3 before: sshll v0.2d, v0.2s, 0 sshll v1.2d, v1.2s, 0 cmgt v2.2d, v1.2d, v0.2d bsl v2.16b, v0.16b, v1.16b xtn v0.2s, v2.2d after: smin v0.2s, v0.2s, v1.2s Require the wide vector MIN or MAX to have one use. A shared wide result would otherwise gain a second narrow operation. Bootstrapped and tested on aarch64-none-linux-gnu. Ok for trunk? Thanks, Kyrill gcc/ChangeLog: * match.pd ((type) minmax ((wide_type) a, (wide_type) b)): Accept vector types, using element_precision and requiring the narrow operation to be supported. gcc/testsuite/ChangeLog: * g++.dg/tree-ssa/vec-narrow-1.C: New test. * g++.dg/tree-ssa/vec-narrow-minmax-2.C: New test.
OK jeff
