Hi!
Apparently for C sizeof on VLA the FE tends to emit something that
is folded into a COMPOUND_EXPR with the VLA decl on lhs and the actual
condition on rhs. In the bar routine in the testcase I'm actually
testing a case where there are multiple such COMPOUND_EXPRs.
This patch accepts those and moves those to the non-decl operand of
the comparison, which is really the only spot where it could be actually
used anyway.
Bootstrapped/regtested on x86_64-linux and i686-linux, committed to trunk,
queued for backporting to release branches.
2017-07-27 Jakub Jelinek <ja...@redhat.com>
PR c/45784
* c-omp.c (c_finish_omp_for): If the condition is wrapped in
rhs of COMPOUND_EXPR(s), skip them and readd their lhs into
new COMPOUND_EXPRs around the rhs of the comparison.
* testsuite/libgomp.c/pr45784.c: New test.
* testsuite/libgomp.c++/pr45784.C: New test.
--- gcc/c-family/c-omp.c.jj 2017-01-01 12:45:46.000000000 +0100
+++ gcc/c-family/c-omp.c 2017-07-27 18:33:40.764274882 +0200
@@ -531,6 +531,12 @@ c_finish_omp_for (location_t locus, enum
{
bool cond_ok = false;
+ /* E.g. C sizeof (vla) could add COMPOUND_EXPRs with
+ evaluation of the vla VAR_DECL. We need to readd
+ them to the non-decl operand. See PR45784. */
+ while (TREE_CODE (cond) == COMPOUND_EXPR)
+ cond = TREE_OPERAND (cond, 1);
+
if (EXPR_HAS_LOCATION (cond))
elocus = EXPR_LOCATION (cond);
@@ -605,6 +611,21 @@ c_finish_omp_for (location_t locus, enum
else if (code != CILK_SIMD && code != CILK_FOR)
cond_ok = false;
}
+
+ if (cond_ok && TREE_VEC_ELT (condv, i) != cond)
+ {
+ tree ce = NULL_TREE, *pce = &ce;
+ tree type = TREE_TYPE (TREE_OPERAND (cond, 1));
+ for (tree c = TREE_VEC_ELT (condv, i); c != cond;
+ c = TREE_OPERAND (c, 1))
+ {
+ *pce = build2 (COMPOUND_EXPR, type, TREE_OPERAND (c, 0),
+ TREE_OPERAND (cond, 1));
+ pce = &TREE_OPERAND (*pce, 1);
+ }
+ TREE_OPERAND (cond, 1) = ce;
+ TREE_VEC_ELT (condv, i) = cond;
+ }
}
if (!cond_ok)
--- libgomp/testsuite/libgomp.c/pr45784.c.jj 2017-07-27 18:50:53.230801321
+0200
+++ libgomp/testsuite/libgomp.c/pr45784.c 2017-07-27 18:51:08.436617805
+0200
@@ -0,0 +1,41 @@
+/* PR c/45784 */
+/* { dg-do run } */
+
+void
+foo (int n)
+{
+ char *p, vla[2 * n];
+ int i;
+ #pragma omp parallel for
+ for (p = vla; p < vla + (sizeof (vla) / sizeof (vla[0])); p++)
+ *p = ' ';
+ #pragma omp parallel for
+ for (i = 0; i < 2 * n; i++)
+ if (vla[i] != ' ')
+ __builtin_abort ();
+}
+
+void
+bar (int n)
+{
+ char *p, vla1[n], vla2[n * 2], vla3[n * 3], vla4[n * 4];
+ int i;
+ __builtin_memset (vla4, ' ', n * 4);
+ #pragma omp parallel for
+ for (p = vla4 + sizeof (vla1); p < vla4 + sizeof (vla3) - sizeof (vla2) +
sizeof (vla1); p += sizeof (vla4) / sizeof (vla4))
+ p[0] = '!';
+ #pragma omp parallel for
+ for (i = 0; i < n * 4; i++)
+ if (vla4[i] != ((i >= n && i < 2 * n) ? '!' : ' '))
+ __builtin_abort ();
+}
+
+int
+main ()
+{
+ volatile int n;
+ n = 128;
+ foo (n);
+ bar (n);
+ return 0;
+}
--- libgomp/testsuite/libgomp.c++/pr45784.C.jj 2017-07-27 18:51:38.545254431
+0200
+++ libgomp/testsuite/libgomp.c++/pr45784.C 2017-07-27 18:51:32.404328545
+0200
@@ -0,0 +1,5 @@
+// PR c/45784
+// { dg-do run }
+
+#include "../libgomp.c/pr45784.c"
+
Jakub
