https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96864
Bug ID: 96864
Summary: loop not vectorized due to cost model
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: crazylht at gmail dot com
CC: hjl.tools at gmail dot com
Target Milestone: ---
cat test.c
---
double d1[1024], d2[1024];
char c1[1024];
int test4(int n)
{
int i;
for (int i = 0; i < 1024; i++)
c1[i] = d1[i] > d2[i] ? c1[i] : 1;
}
---
loop is not vectorized with under -mtune=skylake-avx512 but success with
-mtune=generic
Refer to https://godbolt.org/z/xPGhTh
output of -fopt-info-all
---
Unit growth for small function inlining: 16->16 (0%)
Inlined 0 calls, eliminated 0 functions
test.c:6:5: missed: couldn't vectorize loop
test.c:7:17: missed: not vectorized: no vectype for stmt: _1 = d1[i_13];
scalar_type: double
test.c:6:5: note: ***** Analysis failed with vector mode V4DF
test.c:6:5: note: ***** Skipping vector mode V32QI, which would repeat the
analysis for V4DF
test.c:3:5: note: vectorized 0 loops in function.
test.c:3:5: note: ***** Analysis failed with vector mode VOID
test.c:7:13: note: ***** Analysis failed with vector mode V4DF
test.c:7:13: note: ***** Skipping vector mode V32QI, which would repeat the
analysis for V4DF
test.c:7:13: note: ***** Analysis failed with vector mode V32QI
test.c:7:13: note: ***** Skipping vector mode V32QI, which would repeat the
analysis for V32QI
test.c:6:5: note: ***** Analysis failed with vector mode V32QI
test.c:6:5: note: ***** Skipping vector mode V32QI, which would repeat the
analysis for V32QI
test.c:6:5: note: ***** Analysis failed with vector mode VOID
test.c:8:1: note: ***** Analysis failed with vector mode VOID
---
Seems problem of cost model.
