Andrew,
Here is the new patch that I am currently testing with your change and
incorporating Eric's comment. I included both test cases but renamed
yours and put it into gcc.dg/torture. Does the code in combine.c to
address Eric's comment look OK to you?
Steve Ellcey
steve.ell...@imgtec.com
2015-10-21 Steve Ellcey <sell...@imgtec.com>
Andrew Pinski <apin...@cavium.com>
* combine.c (simplify_comparison): Use gen_lowpart_or_truncate instead
of gen_lowpart when we had a truncating and.
diff --git a/gcc/combine.c b/gcc/combine.c
index fd3e19c..7568ebb 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -11529,8 +11529,8 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx
*pop1)
tmode != GET_MODE (op0); tmode = GET_MODE_WIDER_MODE (tmode))
if ((unsigned HOST_WIDE_INT) c0 == GET_MODE_MASK (tmode))
{
- op0 = gen_lowpart (tmode, inner_op0);
- op1 = gen_lowpart (tmode, inner_op1);
+ op0 = gen_lowpart_or_truncate (tmode, inner_op0);
+ op1 = gen_lowpart_or_truncate (tmode, inner_op1);
code = unsigned_condition (code);
changed = 1;
break;
@@ -12048,12 +12048,9 @@ simplify_comparison (enum rtx_code code, rtx *pop0,
rtx *pop1)
& GET_MODE_MASK (mode))
+ 1)) >= 0
&& const_op >> i == 0
- && (tmode = mode_for_size (i, MODE_INT, 1)) != BLKmode
- && (TRULY_NOOP_TRUNCATION_MODES_P (tmode, GET_MODE (op0))
- || (REG_P (XEXP (op0, 0))
- && reg_truncated_to_mode (tmode, XEXP (op0, 0)))))
+ && (tmode = mode_for_size (i, MODE_INT, 1)) != BLKmode)
{
- op0 = gen_lowpart (tmode, XEXP (op0, 0));
+ op0 = gen_lowpart_or_truncate (tmode, XEXP (op0, 0));
continue;
}
2015-10-21 Steve Ellcey <sell...@imgtec.com>
Andrew Pinski <apin...@cavium.com>
* gcc.dg/torture/pr67736.c: New test.
* gcc.dg/combine-subregs.c: New test.
diff --git a/gcc/testsuite/gcc.dg/combine-subregs.c
b/gcc/testsuite/gcc.dg/combine-subregs.c
index e69de29..c480f88 100644
--- a/gcc/testsuite/gcc.dg/combine-subregs.c
+++ b/gcc/testsuite/gcc.dg/combine-subregs.c
@@ -0,0 +1,36 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -fexpensive-optimizations" } */
+
+#include <inttypes.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
index e69de29..b45874e 100644
--- a/gcc/testsuite/gcc.dg/torture/pr67736.c
+++ b/gcc/testsuite/gcc.dg/torture/pr67736.c
@@ -0,0 +1,32 @@
+/* { dg-do run } */
+
+#include <stdlib.h>
+
+typedef unsigned long long uint64_t;
+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;
+}
