Fixes bugs in sign-extension and selection-with-zero, speeds up integ…

…er division
doe300 · Jul 8, 2018 · f13120d · f13120d
1 parent 637cc71
commit f13120d
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Showing 3 changed files with 16 additions and 15 deletions.
diff --git a/src/intermediate/TypeConversions.cpp b/src/intermediate/TypeConversions.cpp
@@ -265,7 +265,7 @@ InstructionWalker intermediate::insertZeroExtension(InstructionWalker it, Method
         // do nothing, is just a move, since we truncate the 64-bit integers anyway
         it.emplace(new MoveOperation(dest, src, conditional, setFlags));
     }
-    else if(dest.type.getScalarBitCount() == 32 && src.hasType(ValueType::REGISTER) &&
+    else if(src.hasType(ValueType::REGISTER) &&
         (has_flag(src.reg.file, RegisterFile::PHYSICAL_A) || has_flag(src.reg.file, RegisterFile::ACCUMULATOR)) &&
         src.type.getScalarBitCount() == 8)
     {
@@ -300,7 +300,7 @@ InstructionWalker intermediate::insertSignExtension(InstructionWalker it, Method
         // do nothing, is just a move, since we truncate the 64-bit integers anyway
         it.emplace(new MoveOperation(dest, src, conditional, setFlags));
     }
-    else if(dest.type.getScalarBitCount() == 32 && src.hasType(ValueType::REGISTER) &&
+    else if(src.hasType(ValueType::REGISTER) &&
         (has_flag(src.reg.file, RegisterFile::PHYSICAL_A) || has_flag(src.reg.file, RegisterFile::ACCUMULATOR)) &&
         src.type.getScalarBitCount() == 16)
     {
@@ -312,15 +312,14 @@ InstructionWalker intermediate::insertSignExtension(InstructionWalker it, Method
     else
     {
         // out = asr(shl(in, bit_diff) bit_diff)
-        Value widthDiff(
-            Literal(static_cast<int32_t>(dest.type.getScalarBitCount() - src.type.getScalarBitCount())), TYPE_INT8);
+        // where bit_diff is the difference to full 32-bit
+        Value widthDiff(Literal(static_cast<int32_t>(32 - src.type.getScalarBitCount())), TYPE_INT8);
 
         if(!allowLiteral)
         {
             Value tmp = method.addNewLocal(TYPE_INT8, "%sext");
             it.emplace(new LoadImmediate(tmp, widthDiff.literal));
             it.nextInBlock();
-
             widthDiff = tmp;
         }
 

diff --git a/src/intrinsics/Operators.cpp b/src/intrinsics/Operators.cpp
@@ -273,26 +273,23 @@ InstructionWalker intermediate::intrinsifyUnsignedIntegerDivision(
         it.nextInBlock();
         remainder = newRemainder;
         // if R >= D then
+        // R = R >= D ? R - D : R <=> R = R - D >= 0 ? R - D : R <=> R = R - D < 0 ? R : R - D
         const Value tmp = method.addNewLocal(op.getOutput()->type, "%udiv.tmp");
-        it.emplace(new Operation(OP_MAX, tmp, remainder, divisor));
+        it.emplace(new Operation(OP_SUB, tmp, remainder, divisor, COND_ALWAYS, SetFlag::SET_FLAGS));
         it.nextInBlock();
-        it.emplace(new Operation(OP_XOR, NOP_REGISTER, tmp, remainder, COND_ALWAYS, SetFlag::SET_FLAGS));
-        it.nextInBlock();
-        // R := R - D
         newRemainder = method.addNewLocal(op.getOutput()->type, "%udiv.remainder");
-        it.emplace(new Operation(OP_SUB, newRemainder, remainder, divisor, COND_ZERO_SET));
+        it.emplace(new MoveOperation(newRemainder, tmp, COND_NEGATIVE_CLEAR));
         it.nextInBlock();
-        // else R(new) := R(old)
-        it.emplace(new MoveOperation(newRemainder, remainder, COND_ZERO_CLEAR));
+        it.emplace(new MoveOperation(newRemainder, remainder, COND_NEGATIVE_SET));
         it.nextInBlock();
         remainder = newRemainder;
         // Q(i) := 1
         Value newQuotient = method.addNewLocal(op.getOutput()->type, "%udiv.quotient");
-        it.emplace(new Operation(
-            OP_OR, newQuotient, quotient, Value(Literal(static_cast<int32_t>(1) << i), TYPE_INT32), COND_ZERO_SET));
+        it.emplace(new Operation(OP_OR, newQuotient, quotient, Value(Literal(static_cast<int32_t>(1) << i), TYPE_INT32),
+            COND_NEGATIVE_CLEAR));
         it.nextInBlock();
         // else Q(new) := Q(old)
-        it.emplace(new MoveOperation(newQuotient, quotient, COND_ZERO_CLEAR));
+        it.emplace(new MoveOperation(newQuotient, quotient, COND_NEGATIVE_SET));
         it.nextInBlock();
         quotient = newQuotient;
     }

diff --git a/src/optimization/Combiner.cpp b/src/optimization/Combiner.cpp
@@ -747,6 +747,11 @@ InstructionWalker optimizations::combineSelectionWithZero(
     if(it->conditional == COND_ALWAYS || nextIt->conditional == COND_ALWAYS ||
         !it->conditional.isInversionOf(nextIt->conditional))
         return it;
+    // For conditional moves, the source could be written conditionally
+    // TODO improve by removing the condition of the source and allow combining
+    // XXX actually would need to check if the condition is the same as the condition for the moves
+    if(it->hasConditionalExecution() || nextIt->hasConditionalExecution())
+        return it;
     // we have two consecutive moves to the same value, without side-effects and inverted conditions.
     // additionally, one of the moves writes a zero-vale
     if(move->getSource().hasLiteral(INT_ZERO.literal) && !nextMove->getSource().hasLiteral(INT_ZERO.literal))