re PR rtl-optimization/67736 (Wrong optimization with -fexpensive-optimizations on mips64el)

2015-10-23  Steve Ellcey  <sellcey@imgtec.com>
	    Andrew Pinski  <apinski@cavium.com>

	PR rtl-optimization/67736
	* gcc.dg/torture/pr67736.c: New test.
	* gcc.dg/combine-subregs.c: New test.

Co-Authored-By: Andrew Pinski <apinski@cavium.com>

From-SVN: r229260

3 files changed, 75 insertions, 0 deletions

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f13e8dc..1d21435 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2015-10-23  Steve Ellcey  <sellcey@imgtec.com>
+	    Andrew Pinski  <apinski@cavium.com>
+
+	PR rtl-optimization/67736
+	* combine.c (simplify_comparison): Use gen_lowpart_or_truncate instead
+	of gen_lowpart.
+
 2015-10-23  Alan Hayward <alan.hayward@arm.com>
 
 	PR tree-optimization/65947
diff --git a/gcc/testsuite/gcc.dg/combine-subregs.c b/gcc/testsuite/gcc.dg/combine-subregs.c
new file mode 100644
index 0000000..ccace23
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/combine-subregs.c
@@ -0,0 +1,36 @@
+/* { dg-do run { target { stdint_types } } } */
+/* { dg-options "-O2" } */
+
+#include <stdint.h>
+#include <stdlib.h>
+
+void __attribute__ ((noinline))
+foo (uint64_t state, uint32_t last)
+{
+  if (state == last) abort ();
+}
+
+/* This function may do a bad comparision by trying to
+   use SUBREGS during the compare on machines where comparing
+   two registers always compares the entire register regardless
+   of mode.  */
+
+int __attribute__ ((noinline))
+compare (uint64_t state, uint32_t *last, uint8_t buf)
+{
+    if (*last == ((state | buf) & 0xFFFFFFFF)) {
+	foo (state, *last);
+        return 0;
+    }
+    return 1;
+}
+
+int
+main(int argc, char **argv) {
+    uint64_t state = 0xF00000100U;
+    uint32_t last  = 0x101U;
+    int ret        = compare(state, &last, 0x01);
+    if (ret != 0)
+	abort ();
+    exit (0);
+}
diff --git a/gcc/testsuite/gcc.dg/torture/pr67736.c b/gcc/testsuite/gcc.dg/torture/pr67736.c
new file mode 100644
index 0000000..024bb20
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr67736.c
@@ -0,0 +1,32 @@
+/* { dg-do run { target { stdint_types } } } */
+
+#include <stdint.h>
+#include <stdlib.h>
+
+void f(uint64_t *a, uint64_t aa) __attribute__((noinline));
+void f(uint64_t *a, uint64_t aa)
+{
+  uint64_t new_value = aa;
+  uint64_t old_value = *a;
+  int bit_size = 32;
+    uint64_t mask = (uint64_t)(unsigned)(-1);
+    uint64_t tmp = old_value & mask;
+    new_value &= mask;
+    /* On overflow we need to add 1 in the upper bits */
+    if (tmp > new_value)
+        new_value += 1ull<<bit_size;
+    /* Add in the upper bits from the old value */
+    new_value += old_value & ~mask;
+    *a = new_value;
+}
+int main(void)
+{
+  uint64_t value, new_value, old_value;
+  value = 0x100000001;
+  old_value = value;
+  new_value = (value+1)&(uint64_t)(unsigned)(-1);
+  f(&value, new_value);
+  if (value != old_value+1)
+    __builtin_abort ();
+  return 0;
+}