diff mbox series

[7/8] cfg: call simplify_memops() unconditionally.

Message ID 20201116222927.51939-8-luc.vanoostenryck@gmail.com (mailing list archive)
State Mainlined, archived
Headers show
Series cfg: early CFG simplification | expand

Commit Message

Luc Van Oostenryck Nov. 16, 2020, 10:29 p.m. UTC 
Currently, in the main optimization loop, simplify_memops()
is only called if REPEAT_SYMBOL_CLEANUP have been set. This
has (at least) two problems:
1) simplify_memops() may itself create other 'symbol cleanup'
   opportunities. That's fine and when it happens REPEAT_SYMBOL_CLEANUP
   is correctly set but this is directly lost because repeat_phase
   is cleared just after. So, loads and stores are not always
   optimized away as they should.
2) Loads & stores are not always done directly on symbols, in
   fact, it often happens that they are done on some PSEUDO_REG.
   Here too, loads and stores are not always optimized away as
   they should.

So, call simplify_memops() unconditionally.

Note: this have only very small effects on the tests' running time:
	  before		after		  after too
	  real	 4m18.001s	real   4m18.655s  real	 4m19.4
	  user	71m32.911s	user  72m02.701s  user	72m06.6
	  sys	29m06.523s	sys   29m01.721s  sys	29m06.8
      which is under the noise I usually have.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 memops.c                           |  2 ++
 optimize.c                         |  4 +---
 validation/optim/memops-missed01.c | 23 +++++++++++++++++++++++
 validation/optim/memops-missed02.c | 14 ++++++++++++++
 4 files changed, 40 insertions(+), 3 deletions(-)
 create mode 100644 validation/optim/memops-missed01.c
 create mode 100644 validation/optim/memops-missed02.c
diff mbox series

Patch

diff --git a/memops.c b/memops.c
index f071e556da8a..badcdbbb9378 100644
--- a/memops.c
+++ b/memops.c
@@ -146,10 +146,12 @@  static void simplify_loads(struct basic_block *bb)
 				}
 				rewrite_load_instruction(insn, dominators);
 			} else {	// cleanup pending phi-sources
+				int repeat = repeat_phase;
 				pseudo_t phi;
 				FOR_EACH_PTR(dominators, phi) {
 					kill_instruction(phi->def);
 				} END_FOR_EACH_PTR(phi);
+				repeat_phase = repeat;
 			}
 		}
 next_load:
diff --git a/optimize.c b/optimize.c
index bfab74c01b62..8ab105bccdce 100644
--- a/optimize.c
+++ b/optimize.c
@@ -84,9 +84,7 @@  repeat:
 				kill_unreachable_bbs(ep);
 
 			cse_eliminate(ep);
-
-			if (repeat_phase & REPEAT_SYMBOL_CLEANUP)
-				simplify_memops(ep);
+			simplify_memops(ep);
 		} while (repeat_phase);
 		pack_basic_blocks(ep);
 		if (repeat_phase & REPEAT_CFG_CLEANUP)
diff --git a/validation/optim/memops-missed01.c b/validation/optim/memops-missed01.c
new file mode 100644
index 000000000000..fc616f1976a1
--- /dev/null
+++ b/validation/optim/memops-missed01.c
@@ -0,0 +1,23 @@ 
+void bar(int);
+
+void foo(void)
+{
+	char buf[1] = { 42 };
+	const char *p = buf;
+	const char **q = &p;
+	int ch = 0;
+	switch (**q) {
+	case 4:
+		ch = 2;
+	}
+	bar(ch);
+}
+
+/*
+ * check-name: memops-missed01
+ * check-command: test-linearize -Wno-decl $file
+ *
+ * check-output-ignore
+ * check-output-excludes: store\\.
+ * check-output-excludes: load\\.
+ */
diff --git a/validation/optim/memops-missed02.c b/validation/optim/memops-missed02.c
new file mode 100644
index 000000000000..6f0286497943
--- /dev/null
+++ b/validation/optim/memops-missed02.c
@@ -0,0 +1,14 @@ 
+void foo(int a[])
+{
+	int i, val;
+	for (;; i++)
+		val = a[i] ? a[i] : val;
+}
+
+/*
+ * check-name: memops-missed02
+ * check-command: test-linearize -Wno-decl $file
+ *
+ * check-output-ignore
+ * check-output-pattern(1): load\\.
+ */