On 6/7/18 8:16 PM, Peter Bergner wrote:
> On 6/7/18 5:12 PM, Peter Bergner wrote:
>> Is this ok for trunk and the release branches where the earlier fixes
>> were backported to, assuming no bootstrap errors and the testsuite runs
>> do not show any regressions?
>
> Hold off for now. I'm seeing a TImode issue I need to debug first.
The fix for PR83969 accidentally disallowed PRE_INC and PRE_DEC addresses
from being matched for the Y constraint leading to poor code generation.
The old PRE_INC and PRE_DEC addresses were originally accepted via the
address_offset() call and test, but the fix for PR83969 added the test
for rs6000_offsettable_memref_p() and that doesn't accept PRE_INC/PRE_DEC.
My earlier patch just tried moving the rs6000_offsettable_memref_p() call
to after the address_offset() call, but I now remember why I had it placed
before it. The problem was that the address_offset() call and test was
incorrectly accepting some non-offsetable addresses, so we need to test for
rs6000_offsettable_memref_p() first. However, rs6000_offsettable_memref_p()
doesn't accept PRE_INC/PRE_DEC addresses, so the fix used here is to just
test for them explicitly before the other tests, which fixes the reported
bug and doesn't regress the older bugs.
Is this ok for trunk and after some trunk burn in, the GCC 8 and 7 release
branches where the earlier fixes were backported to? All bootstrap builds
completed and the testsuite runs all showed no regressions.
gcc/
PR target/85755
* config/rs6000/rs6000.c (mem_operand_gpr): Enable PRE_INC and PRE_DEC
addresses.
gcc/testsuite/
PR target/85755
* gcc.target/powerpc/pr85755.c: New test.
Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c (revision 261279)
+++ gcc/config/rs6000/rs6000.c (working copy)
@@ -7997,6 +7997,13 @@ mem_operand_gpr (rtx op, machine_mode mo
int extra;
rtx addr = XEXP (op, 0);
+ /* PR85755: Allow PRE_INC and PRE_DEC addresses. */
+ if (TARGET_UPDATE
+ && (GET_CODE (addr) == PRE_INC || GET_CODE (addr) == PRE_DEC)
+ && mode_supports_pre_incdec_p (mode)
+ && legitimate_indirect_address_p (XEXP (addr, 0), false))
+ return true;
+
/* Don't allow non-offsettable addresses. See PRs 83969 and 84279. */
if (!rs6000_offsettable_memref_p (op, mode, false))
return false;
Index: gcc/testsuite/gcc.target/powerpc/pr85755.c
===================================================================
--- gcc/testsuite/gcc.target/powerpc/pr85755.c (nonexistent)
+++ gcc/testsuite/gcc.target/powerpc/pr85755.c (working copy)
@@ -0,0 +1,24 @@
+/* { dg-do compile { target { powerpc*-*-* } } } */
+/* { dg-skip-if "" { powerpc*-*-darwin* } } */
+/* { dg-require-effective-target powerpc_p8vector_ok } */
+/* { dg-skip-if "do not override -mcpu" { powerpc*-*-* } { "-mcpu=*" } {
"-mcpu=power8" } } */
+/* { dg-options "-O1 -mcpu=power8" } */
+
+void
+preinc (long *q, long n)
+{
+ long i;
+ for (i = 0; i < n; i++)
+ q[i] = i;
+}
+
+void
+predec (long *q, long n)
+{
+ long i;
+ for (i = n; i >= 0; i--)
+ q[i] = i;
+}
+
+/* { dg-final { scan-assembler-times {\mstdu\M} 2 } } */
+/* { dg-final { scan-assembler-not {\mstfdu\M} } } */
