match.pd: Simplify BFR of insert when extracting exactly all inserted bits [PR108688]

On Thu, Feb 09, 2023 at 09:16:17AM +0100, Richard Biener via Gcc-patches wrote:
> Hmm.  Can we handle the case of the extraction exactly covering the
> insertion separately then and simplify to plain @1?

I was suggesting that in the PR.  Here it is as an incremental patch
on top of Andrew's patch.

On the newly added testcase the ifcvt-folding difference without/with the
incremental patch is:
--- pr108688.c.171t.ifcvt_      2023-02-09 10:47:30.169916845 +0100
+++ pr108688.c.171t.ifcvt       2023-02-09 10:48:44.942793453 +0100
@@ -25,6 +25,8 @@ Number of blocks in CFG: 11
 Number of blocks to update: 5 ( 45%)

+Applying pattern match.pd:7487, gimple-match.cc:243200
+Applying pattern match.pd:3987, gimple-match.cc:75423
 Matching expression match.pd:1677, gimple-match.cc:209
 Applying pattern match.pd:1733, gimple-match.cc:109481
 Matching expression match.pd:2393, gimple-match.cc:852
@@ -70,7 +72,6 @@ void foo ()
   signed char _29;
   <unnamed-signed:7> _30;
   unsigned int ivtmp_33;
-  <unnamed-signed:7> _ifc__35;
   unsigned char _ifc__37;
   unsigned char _ifc__38;
   unsigned char _ifc__39;
@@ -91,8 +92,7 @@ void foo ()
   _2 = (<unnamed-signed:7>) a.0_1;
   _ifc__38 = u.D.2741;
   _ifc__39 = BIT_INSERT_EXPR <_ifc__38, _2, 0 (7 bits)>;
-  _ifc__35 = BIT_FIELD_REF <_ifc__39, 7, 0>;
-  _4 = (signed char) _ifc__35;
+  _4 = (signed char) _2;
   b.1_5 = b;
   _6 = (signed char) b.1_5;
   _7 = _4 ^ _6;

2023-02-09  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/108688
	* match.pd (bit_field_ref [bit_insert]): Simplify BIT_FIELD_REF
	of BIT_INSERT_EXPR extracting exactly all inserted bits even
	when without mode precision.  Formatting fixes.

	* gcc.c-torture/compile/pr108688-1.c: Add PR number as comment.
	* gcc.dg/pr108688.c: New test.

0 files changed, 0 insertions, 0 deletions