From: Richard Biener <rguenther@suse.de>
Date: Tue, 7 Jan 2025 12:18:27 +0000 (+0100)
Subject: rtl-optimization/118298 - constant iteration loops and #pragma unroll
X-Git-Tag: basepoints/gcc-16~2901
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=34501ef418da13b361614235077c2162caabab73;p=thirdparty%2Fgcc.git

rtl-optimization/118298 - constant iteration loops and #pragma unroll

When the RTL unroller handles constant iteration loops it bails out
prematurely when heuristics wouldn't apply any unrolling before
checking #pragma unroll.

	PR rtl-optimization/118298
	* loop-unroll.cc (decide_unroll_constant_iterations): Honor
	loop->unroll even if the loop is too big for heuristics.
---

diff --git a/gcc/loop-unroll.cc b/gcc/loop-unroll.cc
index 2bd6e888b266..b49520553182 100644
--- a/gcc/loop-unroll.cc
+++ b/gcc/loop-unroll.cc
@@ -372,7 +372,8 @@ decide_unroll_constant_iterations (class loop *loop, int flags)
     nunroll = targetm.loop_unroll_adjust (nunroll, loop);
 
   /* Skip big loops.  */
-  if (nunroll <= 1)
+  if (nunroll <= 1
+      && !(loop->unroll > 1 && loop->unroll < USHRT_MAX))
     {
       if (dump_file)
 	fprintf (dump_file, ";; Not considering loop, is too big\n");