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Re: [PATCH 4/4][AArch64] Cost CCMP instruction sequences to choose better expand order
- From: Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>
- To: Andreas Schwab <schwab at linux-m68k dot org>, Richard Henderson <rth at redhat dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Christophe Lyon <christophe dot lyon at linaro dot org>, nd <nd at arm dot com>
- Date: Mon, 25 Jan 2016 20:09:39 +0000
- Subject: Re: [PATCH 4/4][AArch64] Cost CCMP instruction sequences to choose better expand order
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- References: <000301d11e2c$ca46b1c0$5ed41540$ at arm dot com>,<m237tomvdu dot fsf at linux-m68k dot org>
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Andreas Schwab <schwab@linux-m68k.org> wrote:
> FAIL: gcc.target/aarch64/ccmp_1.c scan-assembler-times \tcmp\tw[0-9]+, 0 4
> FAIL: gcc.target/aarch64/ccmp_1.c scan-assembler adds\t
> FAIL: gcc.target/aarch64/ccmp_1.c scan-assembler-times fccmpe\t.*0\\.0 1
Yes I noticed those too, and here is the fix. Richard's recent change added UNSPEC to the CCMP patterns to stop combine optimizing the CCMP CCmode immediate in a rare case. This requires a change to the CCMP cost calculation as the CCMP instruction with unspec is no longer recognized.
Fix the ccmp_1.c test to allow both '0' and 'wzr' on cmp - BTW is there a regular expression that correctly implements (0|xzr)? If I use that the test still fails somehow but \[0wzr\]+ works fine... Is the correct syntax documented somewhere?
Finally to ensure FCCMPE is emitted on relational compares, add -ffinite-math-only.
ChangeLog:
2016-01-25 Wilco Dijkstra <wdijkstr@arm.com>
gcc/
* config/aarch64/aarch64.c (aarch64_if_then_else_costs):
Remove CONST_INT_P check in CCMP cost calculation.
gcc/testsuite/
* gcc.target/aarch64/ccmp_1.c: Fix test issues.
---
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 6c570c7db1cfbd0415e73fb110ce5d70aa09b540..7f304b78a3e48862bf5aaf855e307fe90969dd8c 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -6014,7 +6014,7 @@ aarch64_if_then_else_costs (rtx op0, rtx op1, rtx op2, int *cost, bool speed)
else if (GET_MODE_CLASS (GET_MODE (inner)) == MODE_CC)
{
/* CCMP. */
- if ((GET_CODE (op1) == COMPARE) && CONST_INT_P (op2))
+ if (GET_CODE (op1) == COMPARE)
{
/* Increase cost of CCMP reg, 0, imm, CC to prefer CMP reg, 0. */
if (XEXP (op1, 1) == const0_rtx)
diff --git a/gcc/testsuite/gcc.target/aarch64/ccmp_1.c b/gcc/testsuite/gcc.target/aarch64/ccmp_1.c
index 7c39b61a585a1d4d662b0736e1c80e06bdc6b4ce..8e3f8629f802eec64c95080a23f320712333471b 100644
--- a/gcc/testsuite/gcc.target/aarch64/ccmp_1.c
+++ b/gcc/testsuite/gcc.target/aarch64/ccmp_1.c
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-O2" } */
+/* { dg-options "-O2 -ffinite-math-only" } */
int
f1 (int a)
@@ -85,7 +85,7 @@ f13 (int a, int b)
/* { dg-final { scan-assembler "cmp\t(.)+34" } } */
/* { dg-final { scan-assembler "cmp\t(.)+35" } } */
-/* { dg-final { scan-assembler-times "\tcmp\tw\[0-9\]+, 0" 4 } } */
+/* { dg-final { scan-assembler-times "\tcmp\tw\[0-9\]+, \[0wzr\]+" 4 } } */
/* { dg-final { scan-assembler-times "fcmpe\t(.)+0\\.0" 2 } } */
/* { dg-final { scan-assembler-times "fcmp\t(.)+0\\.0" 2 } } */