Hi!
This test is dg-do run and invokes UB when these rotate functions
are called with 0 as second argument. There are some other tests
that do this but they are dg-do compile only and not even call those
functions at all, so it IMHO doesn't matter that they are only well
defined for [1,127] and not [0,127].
The following patch fixes it, we pattern recognize both forms as rotates
and we emit identical assembly.
Tested on x86_64-linux -m32/-m64, ok for trunk?
2022-03-23 Jakub Jelinek <ja...@redhat.com>
PR target/102986
* gcc.target/i386/sse2-v1ti-shift-3.c (rotr_v1ti, rotl_v1ti, rotr_ti,
rotl_ti): Use -i&127 instead of 128-i to avoid UB on i == 0.
--- gcc/testsuite/gcc.target/i386/sse2-v1ti-shift-3.c.jj 2021-12-30
15:12:43.709143657 +0100
+++ gcc/testsuite/gcc.target/i386/sse2-v1ti-shift-3.c 2022-03-23
09:36:41.622181842 +0100
@@ -14,14 +14,14 @@ typedef __int128 ti;
uv1ti ashl_v1ti(uv1ti x, unsigned int i) { return x << i; }
uv1ti lshr_v1ti(uv1ti x, unsigned int i) { return x >> i; }
sv1ti ashr_v1ti(sv1ti x, unsigned int i) { return x >> i; }
-uv1ti rotr_v1ti(uv1ti x, unsigned int i) { return (x >> i) | (x << (128-i)); }
-uv1ti rotl_v1ti(uv1ti x, unsigned int i) { return (x << i) | (x >> (128-i)); }
+uv1ti rotr_v1ti(uv1ti x, unsigned int i) { return (x >> i) | (x << (-i&127)); }
+uv1ti rotl_v1ti(uv1ti x, unsigned int i) { return (x << i) | (x >> (-i&127)); }
uti ashl_ti(uti x, unsigned int i) { return x << i; }
uti lshr_ti(uti x, unsigned int i) { return x >> i; }
sti ashr_ti(sti x, unsigned int i) { return x >> i; }
-uti rotr_ti(uti x, unsigned int i) { return (x >> i) | (x << (128-i)); }
-uti rotl_ti(uti x, unsigned int i) { return (x << i) | (x >> (128-i)); }
+uti rotr_ti(uti x, unsigned int i) { return (x >> i) | (x << (-i&127)); }
+uti rotl_ti(uti x, unsigned int i) { return (x << i) | (x >> (-i&127)); }
void test(ti x)
{
Jakub
