diff options
Diffstat (limited to 'chapter14')
3 files changed, 38 insertions, 3 deletions
diff --git a/chapter14/src/main/java/com/seaofnodes/simple/node/AndNode.java b/chapter14/src/main/java/com/seaofnodes/simple/node/AndNode.java index f4933d9c..91bb13db 100644 --- a/chapter14/src/main/java/com/seaofnodes/simple/node/AndNode.java +++ b/chapter14/src/main/java/com/seaofnodes/simple/node/AndNode.java @@ -21,10 +21,13 @@ public class AndNode extends Node { @Override public Type compute() { - if (in(1)._type instanceof TypeInteger i0 && - in(2)._type instanceof TypeInteger i1) { - if (i0.isConstant() && i1.isConstant()) + if( in(1)._type instanceof TypeInteger i0 && + in(2)._type instanceof TypeInteger i1 ) { + if( i0.isConstant() && i1.isConstant() ) return TypeInteger.constant(i0.value()&i1.value()); + // Sharpen allowed bits if either value is narrowed + long mask = i0.mask() & i1.mask(); + return mask < 0 ? TypeInteger.BOT : TypeInteger.make(0,mask); } return TypeInteger.BOT; } diff --git a/chapter14/src/main/java/com/seaofnodes/simple/type/TypeInteger.java b/chapter14/src/main/java/com/seaofnodes/simple/type/TypeInteger.java index 403cc7bf..aca3e06b 100644 --- a/chapter14/src/main/java/com/seaofnodes/simple/type/TypeInteger.java +++ b/chapter14/src/main/java/com/seaofnodes/simple/type/TypeInteger.java @@ -77,6 +77,25 @@ public class TypeInteger extends Type { public long value() { assert isConstant(); return _min; } + // AND-mask of forced zeros. e.g. unsigned types will return their mask; + // u8 will return 0xFF. But also a range of 16-18 (0x10-0x12) will return + // 0x13 - no value in the range {16,17,18} will allow bit 0x04 to be set. + public long mask() { + if( isHigh() ) return 0; + if( isConstant() ) return _min; + //if( _min<0 ) return -1L; + //if( _max==Long.MAX_VALUE ) return -1L; + // Those bit positions which differ min to max + long x = _min ^ _max; + // Highest '1' bit in the differ set. Since the range is from min to + // max, all values below here are possible. + long ff1 = Long.highestOneBit(x); + // Make a all-1's mask from ff1, and set over the same bits (either min + // or max is ok). + long mask = _min | (ff1-1) | ff1; + return mask; + } + @Override public Type xmeet(Type other) { // Invariant from caller: 'this' != 'other' and same class (TypeInteger) diff --git a/chapter14/src/test/java/com/seaofnodes/simple/Chapter14Test.java b/chapter14/src/test/java/com/seaofnodes/simple/Chapter14Test.java index 682eff15..8b3c3c9a 100644 --- a/chapter14/src/test/java/com/seaofnodes/simple/Chapter14Test.java +++ b/chapter14/src/test/java/com/seaofnodes/simple/Chapter14Test.java @@ -49,6 +49,19 @@ return b; assertEquals(67L, Evaluator.evaluate(stop, 0)); } + + @Test + public void testU8While() { + Parser parser = new Parser( +""" +u8 b = 123; +while( b ) b = b + 456;// Truncate +return b; +"""); + StopNode stop = parser.parse(false).iterate(false); + assertEquals("return Phi(Loop9,123,((Phi_b+456)&255));", stop.toString()); + } + @Test public void testU1() { Parser parser = new Parser( |