On January 19, 2018 10:29:36 PM GMT+01:00, Jakub Jelinek <ja...@redhat.com>
wrote:
>Hi!
>
>THis bug has been introduced 16.5 years ago. If
>simplify_binary_operation_1
>is called with op1 (MEM) on which avoid_constant_pool_reference returns
>something simpler, for UMOD simplification we check that trueop1 is
>CONST_INT and power of 2, but then we use INTVAL of the op1 (MEM).
>
>Fixed by using INTVAL on what we've tested. Additionally, if the value
>has msb set and all other bits clear, exact_log2 will return > 0, but
>INTVAL (trueop1) - 1 will invoke UB. Bootstrapped/regtested on
>x86_64-linux
>and i686-linux, ok for trunk?
OK.
Richard.
>2018-01-19 Jakub Jelinek <ja...@redhat.com>
>
> PR target/83930
> * simplify-rtx.c (simplify_binary_operation_1) <case UMOD>: Use
> UINTVAL (trueop1) instead of INTVAL (op1).
>
> * gcc.dg/pr83930.c: New test.
>
>--- gcc/simplify-rtx.c.jj 2018-01-14 17:16:55.657836138 +0100
>+++ gcc/simplify-rtx.c 2018-01-19 10:24:03.389017997 +0100
>@@ -3411,7 +3411,8 @@ simplify_binary_operation_1 (enum rtx_co
> if (CONST_INT_P (trueop1)
> && exact_log2 (UINTVAL (trueop1)) > 0)
> return simplify_gen_binary (AND, mode, op0,
>- gen_int_mode (INTVAL (op1) - 1, mode));
>+ gen_int_mode (UINTVAL (trueop1) - 1,
>+ mode));
> break;
>
> case MOD:
>--- gcc/testsuite/gcc.dg/pr83930.c.jj 2018-01-19 10:33:16.657831745
>+0100
>+++ gcc/testsuite/gcc.dg/pr83930.c 2018-01-19 10:31:55.383859102 +0100
>@@ -0,0 +1,17 @@
>+/* PR target/83930 */
>+/* { dg-do compile } */
>+/* { dg-options "-Og -fno-tree-ccp -w" } */
>+
>+unsigned __attribute__ ((__vector_size__ (16))) v;
>+
>+static inline void
>+bar (unsigned char d)
>+{
>+ v /= d;
>+}
>+
>+__attribute__ ((always_inline)) void
>+foo (void)
>+{
>+ bar (4);
>+}
>
> Jakub
