aarch64: Fix {ash[lr],lshr}<mode>3 expanders [PR94488]

The following testcase ICEs on aarch64 apparently since the introduction of
the aarch64 port.  The reason is that the {ashl,ashr,lshr}<mode>3 expanders
completely unnecessarily FAIL; if operands[2] is something other than
a CONST_INT or REG or MEM and the middle-end code can't cope with the
pattern giving up in these cases.  All the expanders use general_operand
predicate for the shift amount operand, but then have just a special case
for CONST_INT (if in-bound, emit an immediate shift, otherwise force into
REG), or MEM (force into REG), or REG (that is the case it handles).
In the testcase, operands[2] is a lowpart SUBREG of a REG, which is valid
general_operand.
I don't see any reason what is magic about MEMs that it should be forced
into REG and others like SUBREGs that it shouldn't, there isn't even a
reason to check for !REG_P because force_reg will do nothing if the operand
is already a REG, and otherwise can handle general_operand just fine.

2020-04-07  Jakub Jelinek  <jakub@redhat.com>

	PR target/94488
	* config/aarch64/aarch64-simd.md (ashl<mode>3, lshr<mode>3,
	ashr<mode>3): Force operands[2] into reg whenever it is not CONST_INT.
	Assume it is a REG after that instead of testing it and doing FAIL
	otherwise.  Formatting fix.

	* gcc.c-torture/compile/pr94488.c: New test.

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b5c9aed6701ffbb16f5c3a8eea90a6894f500b1b..8c5e197591b38782148a3cc96f26f2edf3797b68 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -58,6 +58,12 @@
        * config/i386/i386-expand.c (expand_vec_perm_pshufb): Fix the check
        for inter-lane permutation for 64-byte modes.
 
+       PR target/94488
+       * config/aarch64/aarch64-simd.md (ashl<mode>3, lshr<mode>3,
+       ashr<mode>3): Force operands[2] into reg whenever it is not CONST_INT.
+       Assume it is a REG after that instead of testing it and doing FAIL
+       otherwise.  Formatting fix.
+
 2020-04-07  Sebastian Huber  <sebastian.huber@embedded-brains.de>
 
        * config/rs6000/t-rtems: Delete mcpu=8540 multilib.

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 4d547a5baded2ee6ffd07fdd0e3a678b3feb119c..ab04cc08f430d7e583130156b502987d29dfed7e 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -54,6 +54,9 @@
        PR c++/94512
        * g++.dg/gomp/pr94512.C: New test.
 
+       PR target/94488
+       * gcc.c-torture/compile/pr94488.c: New test.
+
        PR target/94500
        * gcc.target/i386/avx512bw-pr94500.c: New test.