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Re: [PATCH][ARM] Fix ldrd offsets
- From: Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>, Ramana Radhakrishnan <Ramana dot Radhakrishnan at arm dot com>, Kyrylo Tkachov <Kyrylo dot Tkachov at arm dot com>
- Cc: nd <nd at arm dot com>
- Date: Thu, 23 Feb 2017 16:57:19 +0000
- Subject: Re: [PATCH][ARM] Fix ldrd offsets
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From: Wilco Dijkstra
Sent: 03 November 2016 12:20
To: GCC Patches
Cc: nd
Subject: [PATCH][ARM] Fix ldrd offsets
Fix ldrd offsets of Thumb-2 - for TARGET_LDRD the range is +-1020,
without -255..4091. This reduces the number of addressing instructions
when using DI mode operations (such as in PR77308).
Bootstrap & regress OK.
ChangeLog:
2015-11-03 Wilco Dijkstra <wdijkstr@arm.com>
gcc/
* config/arm/arm.c (arm_legitimate_index_p): Add comment.
(thumb2_legitimate_index_p): Use correct range for DI/DF mode.
--
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 3c4c7042d9c2101619722b5822b3d1ca37d637b9..5d12cf9c46c27d60a278d90584bde36ec86bb3fe 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -7486,6 +7486,8 @@ arm_legitimate_index_p (machine_mode mode, rtx index, RTX_CODE outer,
{
HOST_WIDE_INT val = INTVAL (index);
+ /* Assume we emit ldrd or 2x ldr if !TARGET_LDRD.
+ If vldr is selected it uses arm_coproc_mem_operand. */
if (TARGET_LDRD)
return val > -256 && val < 256;
else
@@ -7613,11 +7615,13 @@ thumb2_legitimate_index_p (machine_mode mode, rtx index, int strict_p)
if (code == CONST_INT)
{
HOST_WIDE_INT val = INTVAL (index);
- /* ??? Can we assume ldrd for thumb2? */
- /* Thumb-2 ldrd only has reg+const addressing modes. */
- /* ldrd supports offsets of +-1020.
- However the ldr fallback does not. */
- return val > -256 && val < 256 && (val & 3) == 0;
+ /* Thumb-2 ldrd only has reg+const addressing modes.
+ Assume we emit ldrd or 2x ldr if !TARGET_LDRD.
+ If vldr is selected it uses arm_coproc_mem_operand. */
+ if (TARGET_LDRD)
+ return IN_RANGE (val, -1020, 1020) && (val & 3) == 0;
+ else
+ return IN_RANGE (val, -255, 4095 - 4);
}
else
return 0;