From bb3147d5b212d675ca2575ac1b571aaaf478cf5e Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Sun, 15 Sep 2024 13:59:55 -0700
Subject: Folding loads before phis needs more work (#116)

* Folding loads before phis needs more work

Have to check load alias & offset/field match.
Could work for stores as well, will need to check more inputs

* Preserve SAR/SHL sharpness with variant shifts

* phi-node cloning honors unrelated argument types

* bool can never do phiCon

* dont fold shifts outside the range 0-63

* Now allowed to fold Loads in Phi

Because honors glb() of inputs

* Correct shr of mixed sign

* yank load merge again

needs an anti-dep check

* Stop phi-merge if it loses precision

* wrap bug
---
 .../java/com/seaofnodes/simple/Chapter06Test.java  |   2 +-
 .../java/com/seaofnodes/simple/Chapter14Test.java  | 108 +++++++++++++++++++++
 2 files changed, 109 insertions(+), 1 deletion(-)

(limited to 'chapter14/src/test/java/com')

diff --git a/chapter14/src/test/java/com/seaofnodes/simple/Chapter06Test.java b/chapter14/src/test/java/com/seaofnodes/simple/Chapter06Test.java
index cddf0ae2..516dbf09 100644
--- a/chapter14/src/test/java/com/seaofnodes/simple/Chapter06Test.java
+++ b/chapter14/src/test/java/com/seaofnodes/simple/Chapter06Test.java
@@ -65,7 +65,7 @@ else
     b=5;
 return b;""", TypeInteger.BOT);
         StopNode stop = parser.parse().iterate(true);
-        assertEquals("return Phi(Region39,42,5);", stop.toString());
+        assertEquals("return Phi(Region34,42,5);", stop.toString());
     }
 
     @Test
diff --git a/chapter14/src/test/java/com/seaofnodes/simple/Chapter14Test.java b/chapter14/src/test/java/com/seaofnodes/simple/Chapter14Test.java
index 7d6fecf9..0464f3ec 100644
--- a/chapter14/src/test/java/com/seaofnodes/simple/Chapter14Test.java
+++ b/chapter14/src/test/java/com/seaofnodes/simple/Chapter14Test.java
@@ -157,6 +157,19 @@ return j;
         assertEquals(1L, Evaluator.evaluate(stop,  1));
     }
 
+    @Test
+    public void testWrapShr() {
+        Parser parser = new Parser(
+"""
+return (arg >>> 1)==0;
+""");
+        StopNode stop = parser.parse(false).iterate(true);
+        assertEquals("return (!(arg>>>1));", stop.toString());
+        assertEquals(1L, Evaluator.evaluate(stop, 0));
+        assertEquals(1L, Evaluator.evaluate(stop, 1));
+        assertEquals(0L, Evaluator.evaluate(stop, 2));
+    }
+
     @Test
     public void testOr() {
         Parser parser = new Parser(
@@ -180,6 +193,101 @@ return arg;
         catch( Exception e ) { assertEquals("Cannot '&' FltBot",e.getMessage()); }
     }
 
+    @Test
+    public void testLoadBug() {
+        Parser parser = new Parser(
+"""
+struct A { int i; }
+struct B { int i; }
+A a = new A;
+A t1 = new A;
+B b = new B;
+B t2 = new B;
+int i;
+if (arg) i = a.i;
+else     i = b.i;
+return i;
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("return Phi(Region31,.i,.i);", stop.toString());
+        assertEquals(0L, Evaluator.evaluate(stop, 0));
+    }
+
+    @Test
+    public void testBug2() {
+        Parser parser = new Parser(
+"""
+int z = 0;
+while (1) {
+    int j;
+    if (arg&3) {
+        j = arg >> 2;
+    } else {
+        j = (arg >> 3)+z;
+    }
+    return j+1;
+}
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("return ((arg>>Phi(Region32,2,3))+1);", stop.toString());
+        assertEquals(1L, Evaluator.evaluate(stop, 0));
+        assertEquals(1L, Evaluator.evaluate(stop, 1));
+        assertEquals(2L, Evaluator.evaluate(stop, 7));
+        assertEquals(2L, Evaluator.evaluate(stop, 8));
+    }
+
+    @Test
+    public void testBug3() {
+        Parser parser = new Parser(
+"""
+flt f = arg;
+bool b;
+if (arg&3) b = f == 1.0;
+else       b = f == 2.0;
+if (arg&5) b = arg == 1;
+return b;
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("return Phi(Region37,(arg==1),((flt)arg==Phi(Region23,1.0,2.0)));", stop.toString());
+        assertEquals(1L, Evaluator.evaluate(stop, 1));
+        assertEquals(0L, Evaluator.evaluate(stop, 2));
+        assertEquals(0L, Evaluator.evaluate(stop, 3));
+    }
+
+    @Test
+    public void testBug4() {
+        Parser parser = new Parser(
+"""
+int i;
+if (arg&7) i=3;
+else       i=2;
+return (arg == i) == 1;
+""");
+        StopNode stop = parser.parse(false).iterate(true);
+        assertEquals("return (arg==Phi(Region18,3,2));", stop.toString());
+        assertEquals(0L, Evaluator.evaluate(stop,  0));
+        assertEquals(0L, Evaluator.evaluate(stop,  1));
+        assertEquals(0L, Evaluator.evaluate(stop,  2));
+        assertEquals(1L, Evaluator.evaluate(stop,  3));
+    }
+
+    @Test
+    public void testBug5() {
+        Parser parser = new Parser(
+"""
+int d = -1;
+while (1) {
+    int i = (arg & 7) + (9223372036854775807 - 7);
+    if (arg & 1) i = ((arg&3) + (9223372036854775807 - 3)) & d;
+    return i + -1;
+}
+""");
+        StopNode stop = parser.parse(false).iterate(true);
+        assertEquals("return (Phi(Region43,((arg&3)+9223372036854775804),((arg&7)+9223372036854775800))+-1);", stop.toString());
+        assertEquals(0x7FFFFFFFFFFFFFF7L, Evaluator.evaluate(stop,  0));
+        assertEquals(0x7FFFFFFFFFFFFFFCL, Evaluator.evaluate(stop,  1));
+    }
+
     @Test
     public void testTypes() {
         Parser parser = new Parser(
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