Hi all,
This RTL checking error occurs on aarch64 in aarch_accumulator_forwarding when
processing an msubsi insn
with subregs:
(insn 15 14 16 3 (set (reg/v:SI 78 [ i ])
(minus:SI (subreg:SI (reg/v:DI 76 [ aul ]) 0)
(mult:SI (subreg:SI (reg:DI 83) 0)
(subreg:SI (reg:DI 75 [ _20 ]) 0)))) schedice.c:10 357 {*msubsi}
The register_operand predicate for that pattern allows subregs (I think
correctly).
The code in aarch_accumulator_forwarding doesn't take that into account and
ends up
taking a REGNO of a SUBREG, causing a checking error.
This patch fixes that by stripping the subregs off the accumulator rtx before
checking that the inner expression is a REG and taking its REGNO.
The testcase now works fine with an aarch64-none-elf toolchain configure for
RTL checking.
The testcase is taken verbatim from the BZ entry for PR 68088.
Since this function is shared between arm and aarch64 I've bootstrapped and
tested it on both
and I'll need ok's for both ports.
Ok for trunk?
Thanks,
Kyrill
2015-10-28 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
PR target/68088
* config/arm/aarch-common.c (aarch_strip_subreg): New function.
(aarch_accumulator_forwarding): Strip subregs from accumulator rtx
when appropriate.
2015-10-28 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
* gcc.target/aarch64/pr68088_1.c: New test.
commit 7ce1b9ec8b8486cab34071a9c120db13e7c3b96a
Author: Kyrylo Tkachov <kyrylo.tkac...@arm.com>
Date: Tue Oct 27 11:42:19 2015 +0000
[ARM/AArch64] PR 68088: Fix RTL checking ICE due to subregs inside accumulator forwarding check
diff --git a/gcc/config/arm/aarch-common.c b/gcc/config/arm/aarch-common.c
index a940a02..2a21c4e 100644
--- a/gcc/config/arm/aarch-common.c
+++ b/gcc/config/arm/aarch-common.c
@@ -389,6 +389,15 @@ arm_mac_accumulator_is_result (rtx producer, rtx consumer)
&& !reg_overlap_mentioned_p (result, op1));
}
+/* If X is a subreg return the value it contains, otherwise
+ return X unchanged. */
+
+static rtx
+aarch_strip_subreg (rtx x)
+{
+ return GET_CODE (x) == SUBREG ? SUBREG_REG (x) : x;
+}
+
/* Return non-zero if the destination of PRODUCER feeds the accumulator
operand of an MLA-like operation. */
@@ -420,14 +429,14 @@ aarch_accumulator_forwarding (rtx_insn *producer, rtx_insn *consumer)
case PLUS:
/* Possibly an MADD. */
if (GET_CODE (XEXP (mla, 0)) == MULT)
- accumulator = XEXP (mla, 1);
+ accumulator = aarch_strip_subreg (XEXP (mla, 1));
else
return 0;
break;
case MINUS:
/* Possibly an MSUB. */
if (GET_CODE (XEXP (mla, 1)) == MULT)
- accumulator = XEXP (mla, 0);
+ accumulator = aarch_strip_subreg (XEXP (mla, 0));
else
return 0;
break;
@@ -441,7 +450,7 @@ aarch_accumulator_forwarding (rtx_insn *producer, rtx_insn *consumer)
{
/* FMADD/FMSUB. */
- accumulator = XEXP (mla, 2);
+ accumulator = aarch_strip_subreg (XEXP (mla, 2));
}
else if (REG_P (XEXP (mla, 1))
&& GET_CODE (XEXP (mla, 2)) == NEG
@@ -449,7 +458,7 @@ aarch_accumulator_forwarding (rtx_insn *producer, rtx_insn *consumer)
|| GET_CODE (XEXP (mla, 0)) == NEG))
{
/* FNMADD/FNMSUB. */
- accumulator = XEXP (XEXP (mla, 2), 0);
+ accumulator = aarch_strip_subreg (XEXP (XEXP (mla, 2), 0));
}
else
return 0;
@@ -460,6 +469,9 @@ aarch_accumulator_forwarding (rtx_insn *producer, rtx_insn *consumer)
return 0;
}
+ if (!REG_P (accumulator))
+ return 0;
+
return (REGNO (dest) == REGNO (accumulator));
}
diff --git a/gcc/testsuite/gcc.target/aarch64/pr68088_1.c b/gcc/testsuite/gcc.target/aarch64/pr68088_1.c
new file mode 100644
index 0000000..49c6aa1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr68088_1.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+void bar (unsigned long);
+
+void
+foo (unsigned long aul, unsigned m, unsigned i)
+{
+ while (1)
+ {
+ aul += i;
+ i = aul % m;
+ bar (aul);
+ }
+}
