From 41c7cac56c4e6fd1f65281ae3a49bc2308be5191 Mon Sep 17 00:00:00 2001
From: Richard Sandiford <richard.sandiford@arm.com>
Date: Wed, 16 Nov 2016 13:07:08 +0000
Subject: [PATCH] Use df_read_modify_subreg_p in cprop.c
local_cprop_find_used_regs punted on all multiword registers,
with the comment:
/* Setting a subreg of a register larger than word_mode leaves
the non-written words unchanged. */
But this only applies if the outer mode is smaller than the
inner mode. If they're the same size then writes to the subreg
are a normal full update.
This patch uses df_read_modify_subreg_p instead. A later patch
adds more uses of the same routine, but this part had a (positive)
effect on code generation for the testsuite whereas the others
seemed to be simple clean-ups.
gcc/
2016-11-15 Richard Sandiford <richard.sandiford@arm.com>
Alan Hayward <alan.hayward@arm.com>
David Sherwood <david.sherwood@arm.com>
* cprop.c (local_cprop_find_used_regs): Use df_read_modify_subreg_p.
Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r242488
---
gcc/ChangeLog | 6 ++++++
gcc/cprop.c | 4 +---
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a49e02492362..fe32d0f7d312 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-11-16 Richard Sandiford <richard.sandiford@arm.com>
+ Alan Hayward <alan.hayward@arm.com>
+ David Sherwood <david.sherwood@arm.com>
+
+ * cprop.c (local_cprop_find_used_regs): Use df_read_modify_subreg_p.
+
2016-11-16 Richard Biener <rguenther@suse.de>
PR middle-end/78333
diff --git a/gcc/cprop.c b/gcc/cprop.c
index 6b4c0b8fa389..31868a5c6bb4 100644
--- a/gcc/cprop.c
+++ b/gcc/cprop.c
@@ -1161,9 +1161,7 @@ local_cprop_find_used_regs (rtx *xptr, void *data)
return;
case SUBREG:
- /* Setting a subreg of a register larger than word_mode leaves
- the non-written words unchanged. */
- if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
+ if (df_read_modify_subreg_p (x))
return;
break;
--
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