Hi!
On the following testcase we ICE during warn_uninit.
Normally, has_undefined_value_p returns false for anonymous SSA_NAMEs,
so NULL expr/var aren't a problem. If t has a COMPLEX_EXPR as def-stmt,
where the first operand is some scalar var's (D) SSA_NAME and the second
operand is 0, which results from gimplification of conversion of scalar
uninitialized var to complex type, t is anonymous SSA_NAME and expr and var
are both NULL.
This patch attempts to deal with that, try to recognize the case and use
the other SSA_NAME's underlying var as expr/var in that case, or punt (in
the unlikely case this wouldn't help).
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk/6.2?
2016-06-20 Jakub Jelinek <ja...@redhat.com>
PR middle-end/71581
* tree-ssa-uninit.c (warn_uninit): If EXPR and VAR are NULL,
see if T isn't anonymous SSA_NAME with COMPLEX_EXPR created
for conversion of scalar user var to complex type and use the
underlying SSA_NAME_VAR in that case. If EXPR is still NULL,
punt.
* gcc.dg/pr71581.c: New test.
--- gcc/tree-ssa-uninit.c.jj 2016-05-06 15:09:09.000000000 +0200
+++ gcc/tree-ssa-uninit.c 2016-06-20 16:13:31.324052992 +0200
@@ -131,6 +131,29 @@ warn_uninit (enum opt_code wc, tree t, t
if (!has_undefined_value_p (t))
return;
+ /* Anonymous SSA_NAMEs shouldn't be uninitialized, but ssa_undefined_value_p
+ can return true if the def stmt of anonymous SSA_NAME is COMPLEX_EXPR
+ created for conversion from scalar to complex. Use the underlying var of
+ the COMPLEX_EXPRs real part in that case. See PR71581. */
+ if (expr == NULL_TREE
+ && var == NULL_TREE
+ && SSA_NAME_VAR (t) == NULL_TREE
+ && is_gimple_assign (SSA_NAME_DEF_STMT (t))
+ && gimple_assign_rhs_code (SSA_NAME_DEF_STMT (t)) == COMPLEX_EXPR)
+ {
+ tree v = gimple_assign_rhs1 (SSA_NAME_DEF_STMT (t));
+ if (TREE_CODE (v) == SSA_NAME
+ && has_undefined_value_p (v)
+ && zerop (gimple_assign_rhs2 (SSA_NAME_DEF_STMT (t))))
+ {
+ expr = SSA_NAME_VAR (v);
+ var = expr;
+ }
+ }
+
+ if (expr == NULL_TREE)
+ return;
+
/* TREE_NO_WARNING either means we already warned, or the front end
wishes to suppress the warning. */
if ((context
--- gcc/testsuite/gcc.dg/pr71581.c.jj 2016-06-20 16:39:18.825817407 +0200
+++ gcc/testsuite/gcc.dg/pr71581.c 2016-06-20 16:28:49.000000000 +0200
@@ -0,0 +1,24 @@
+/* PR middle-end/71581 */
+/* { dg-do compile } */
+/* { dg-options "-Wuninitialized" } */
+
+_Complex float
+f1 (void)
+{
+ float x;
+ return x; /* { dg-warning "is used uninitialized in this function" } */
+}
+
+_Complex double
+f2 (void)
+{
+ double x;
+ return x; /* { dg-warning "is used uninitialized in this function" } */
+}
+
+_Complex int
+f3 (void)
+{
+ int x;
+ return x; /* { dg-warning "is used uninitialized in this function" } */
+}
Jakub
