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Avoid non-canonical RTL in splitter for adding a large constant to register on the PA
- From: Jeff Law <law at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Thu, 21 May 2015 11:18:26 -0600
- Subject: Avoid non-canonical RTL in splitter for adding a large constant to register on the PA
- Authentication-results: sourceware.org; auth=none
The PA has a splitter to optimize the addition of certain constants to a
register. One of the cases the splitter handles is when the constant
requires 2 insns to generate, is divisible by 2, 4, or 8 and if divided
by 2, 4 or 8 it only needs a single insn to generate the constant.
Obviously the splitter reduces the constant by a scaling factor and
loads that value, then uses a shift-add insn to scale it back up for the
addition to the other operand. That saves us one insn.
That splitter generates the non-canonical MULT form of a shadd. This
patch changes it to use ASHIFT form instead. This fixes all the
regressions seen in my testcase of 300+ files when I remove the
non-canonical shift-add using MULT patterns.
We still have other places that can produce the non-canonical form,
they're just not triggering in that suite of 300+ files. So I'm not
removing the non-canonical shift-add using MULT patterns just yet.
Tested on hppa.exp and the 300 files noted above. Installed on the trunk.
commit 147771b2a45499d118e4c68a7953881f182e1b97
Author: Jeff Law <law@redhat.com>
Date: Thu May 21 11:01:59 2015 -0600
* config/pa/pa.md (add-with-constant splitter): Use ASHIFT rather
than MULT for shadd sequences.
* gcc.target/hppa/shadd-4.c: New test.
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3ec7255..48472bc 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2015-05-21 Jeff Law <law@redhat.com>
+
+ * config/pa/pa.md (add-with-constant splitter): Use ASHIFT rather
+ than MULT for shadd sequences.
+
2015-05-08 Jan Hubicka <hubicka@ucw.cz>
* alias.c (alias_stats): New static var.
diff --git a/gcc/config/pa/pa.md b/gcc/config/pa/pa.md
index 73c8f6b..aaec27d 100644
--- a/gcc/config/pa/pa.md
+++ b/gcc/config/pa/pa.md
@@ -5132,7 +5132,7 @@
(clobber (match_operand:SI 4 "register_operand" ""))]
"! pa_cint_ok_for_move (INTVAL (operands[2]))"
[(set (match_dup 4) (match_dup 2))
- (set (match_dup 0) (plus:SI (mult:SI (match_dup 4) (match_dup 3))
+ (set (match_dup 0) (plus:SI (ashift:SI (match_dup 4) (match_dup 3))
(match_dup 1)))]
"
{
@@ -5147,17 +5147,17 @@
if (intval % 2 == 0 && pa_cint_ok_for_move (intval / 2))
{
operands[2] = GEN_INT (intval / 2);
- operands[3] = const2_rtx;
+ operands[3] = const1_rtx;
}
else if (intval % 4 == 0 && pa_cint_ok_for_move (intval / 4))
{
operands[2] = GEN_INT (intval / 4);
- operands[3] = GEN_INT (4);
+ operands[3] = const2_rtx;
}
else if (intval % 8 == 0 && pa_cint_ok_for_move (intval / 8))
{
operands[2] = GEN_INT (intval / 8);
- operands[3] = GEN_INT (8);
+ operands[3] = GEN_INT (3);
}
else if (pa_cint_ok_for_move (-intval))
{
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 46a6bb7..20a4379 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2015-05-21 Jeff Law <law@redhat.com>
+
+ * gcc.target/hppa/shadd-4.c: New test.
+
2015-05-08 Michael Matz <matz@suse.de>
* gcc.dg/vect/vect-strided-store.c: New test.
diff --git a/gcc/testsuite/gcc.target/hppa/shadd-4.c b/gcc/testsuite/gcc.target/hppa/shadd-4.c
new file mode 100644
index 0000000..e25d148
--- /dev/null
+++ b/gcc/testsuite/gcc.target/hppa/shadd-4.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-times "sh.add" 1 } } */
+unsigned int
+oof (int uid)
+{
+ return (174 << 7) + uid;
+}