Hi!
As the testcase shows, my latest changes caused ICE on that testcase.
The problem is that arith_overflow_check_p now can change the use_stmt
argument (has a reference), so that if it succeeds (returns non-zero),
it points it to the GIMPLE_COND or EQ/NE or COND_EXPR assignment from the
TRUNC_DIV_EXPR assignment.
The problem was that it would change use_stmt also if it returned 0 in some
cases, such as multiple imm uses of the division, and in one of the callers
if arith_overflow_check_p returns 0 it looks at use_stmt again and performs
other checks, which of course assumes that use_stmt is the one passed
to arith_overflow_check_p and not e.g. NULL instead or some other unrelated
stmt.
The following patch fixes that by only changing use_stmt when we are about
to return non-zero (for the MULT_EXPR case, which is the only one with the
need to use different use_stmt).
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2021-01-12 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/98629
* tree-ssa-math-opts.c (arith_overflow_check_p): Don't update use_stmt
unless returning non-zero.
* gcc.c-torture/compile/pr98629.c: New test.
--- gcc/tree-ssa-math-opts.c.jj 2021-01-11 10:35:02.196501461 +0100
+++ gcc/tree-ssa-math-opts.c 2021-01-11 23:56:24.154380944 +0100
@@ -3667,6 +3667,7 @@ arith_overflow_check_p (gimple *stmt, gi
tree rhs1 = gimple_assign_rhs1 (stmt);
tree rhs2 = gimple_assign_rhs2 (stmt);
tree multop = NULL_TREE, divlhs = NULL_TREE;
+ gimple *cur_use_stmt = use_stmt;
if (code == MULT_EXPR)
{
@@ -3697,26 +3698,26 @@ arith_overflow_check_p (gimple *stmt, gi
if (!divlhs)
return 0;
use_operand_p use;
- if (!single_imm_use (divlhs, &use, &use_stmt))
+ if (!single_imm_use (divlhs, &use, &cur_use_stmt))
return 0;
}
- if (gimple_code (use_stmt) == GIMPLE_COND)
+ if (gimple_code (cur_use_stmt) == GIMPLE_COND)
{
- ccode = gimple_cond_code (use_stmt);
- crhs1 = gimple_cond_lhs (use_stmt);
- crhs2 = gimple_cond_rhs (use_stmt);
+ ccode = gimple_cond_code (cur_use_stmt);
+ crhs1 = gimple_cond_lhs (cur_use_stmt);
+ crhs2 = gimple_cond_rhs (cur_use_stmt);
}
- else if (is_gimple_assign (use_stmt))
+ else if (is_gimple_assign (cur_use_stmt))
{
- if (gimple_assign_rhs_class (use_stmt) == GIMPLE_BINARY_RHS)
+ if (gimple_assign_rhs_class (cur_use_stmt) == GIMPLE_BINARY_RHS)
{
- ccode = gimple_assign_rhs_code (use_stmt);
- crhs1 = gimple_assign_rhs1 (use_stmt);
- crhs2 = gimple_assign_rhs2 (use_stmt);
+ ccode = gimple_assign_rhs_code (cur_use_stmt);
+ crhs1 = gimple_assign_rhs1 (cur_use_stmt);
+ crhs2 = gimple_assign_rhs2 (cur_use_stmt);
}
- else if (gimple_assign_rhs_code (use_stmt) == COND_EXPR)
+ else if (gimple_assign_rhs_code (cur_use_stmt) == COND_EXPR)
{
- tree cond = gimple_assign_rhs1 (use_stmt);
+ tree cond = gimple_assign_rhs1 (cur_use_stmt);
if (COMPARISON_CLASS_P (cond))
{
ccode = TREE_CODE (cond);
@@ -3792,11 +3793,17 @@ arith_overflow_check_p (gimple *stmt, gi
{
if ((crhs1 == divlhs && arith_cast_equal_p (crhs2, multop))
|| (crhs2 == divlhs && arith_cast_equal_p (crhs1, multop)))
- return ccode == NE_EXPR ? 1 : -1;
+ {
+ use_stmt = cur_use_stmt;
+ return ccode == NE_EXPR ? 1 : -1;
+ }
}
else if ((crhs1 == divlhs && operand_equal_p (crhs2, multop, 0))
|| (crhs2 == divlhs && crhs1 == multop))
- return ccode == NE_EXPR ? 1 : -1;
+ {
+ use_stmt = cur_use_stmt;
+ return ccode == NE_EXPR ? 1 : -1;
+ }
}
break;
default:
--- gcc/testsuite/gcc.c-torture/compile/pr98629.c.jj 2021-01-12
00:00:21.132949613 +0100
+++ gcc/testsuite/gcc.c-torture/compile/pr98629.c 2021-01-11
23:59:58.178206894 +0100
@@ -0,0 +1,11 @@
+/* PR tree-optimization/98629 */
+
+unsigned int a;
+int b, c;
+
+void
+foo (void)
+{
+ unsigned int *e = &a;
+ (a /= a |= b) - (0 <= (*e += *e)) * (c *= *e);
+}
Jakub
