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changeset 23014:60dd55e84d87

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Tune sign and zero extend canonicalizations to take usage counts of the convert operation and its value into account.
author Thomas Wuerthinger <thomas.wuerthinger@oracle.com>
date Wed, 18 Nov 2015 04:00:32 +0100
parents 79266e707964
children dc609421fcdb
files graal/com.oracle.graal.nodes/src/com/oracle/graal/nodes/calc/CompareNode.java graal/com.oracle.graal.nodes/src/com/oracle/graal/nodes/calc/NarrowNode.java
diffstat 2 files changed, 18 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- a/graal/com.oracle.graal.nodes/src/com/oracle/graal/nodes/calc/CompareNode.java	Tue Nov 17 16:32:15 2015 -0800
+++ b/graal/com.oracle.graal.nodes/src/com/oracle/graal/nodes/calc/CompareNode.java	Wed Nov 18 04:00:32 2015 +0100
@@ -132,6 +132,12 @@
             ConvertNode convertX = (ConvertNode) forX;
             ConvertNode convertY = (ConvertNode) forY;
             if (convertX.preservesOrder(condition()) && convertY.preservesOrder(condition()) && convertX.getValue().stamp().isCompatible(convertY.getValue().stamp())) {
+                boolean multiUsage = (convertX.asNode().getUsageCount() > 1 || convertY.asNode().getUsageCount() > 1);
+                if ((forX instanceof ZeroExtendNode || forX instanceof SignExtendNode) && multiUsage) {
+                    // Do not perform for zero or sign extend if there are multiple usages of the
+                    // value.
+                    return this;
+                }
                 return duplicateModified(convertX.getValue(), convertY.getValue());
             }
         }
@@ -154,6 +160,12 @@
             return optimizeNormalizeCmp(constant, (NormalizeCompareNode) nonConstant, mirrored);
         } else if (nonConstant instanceof ConvertNode) {
             ConvertNode convert = (ConvertNode) nonConstant;
+            boolean multiUsage = (convert.asNode().getUsageCount() > 1 && convert.getValue().getUsageCount() == 1);
+            if ((convert instanceof ZeroExtendNode || convert instanceof SignExtendNode) && multiUsage) {
+                // Do not perform for zero or sign extend if it could introduce
+                // new live values.
+                return this;
+            }
             ConstantNode newConstant = canonicalConvertConstant(tool, convert, constant);
             if (newConstant != null) {
                 if (mirrored) {
--- a/graal/com.oracle.graal.nodes/src/com/oracle/graal/nodes/calc/NarrowNode.java	Tue Nov 17 16:32:15 2015 -0800
+++ b/graal/com.oracle.graal.nodes/src/com/oracle/graal/nodes/calc/NarrowNode.java	Wed Nov 18 04:00:32 2015 +0100
@@ -85,6 +85,12 @@
         } else if (forValue instanceof IntegerConvertNode) {
             // SignExtendNode or ZeroExtendNode
             IntegerConvertNode<?, ?> other = (IntegerConvertNode<?, ?>) forValue;
+            if (other.getValue().getUsageCount() == 1 && other.getUsageCount() > 1) {
+                // Do not perform if this will introduce a new live value.
+                // If the original value's usage count is > 1, there is already another user.
+                // If the convert's usage count is <=1, it will be dead code eliminated.
+                return this;
+            }
             if (getResultBits() == other.getInputBits()) {
                 // xxxx -(extend)-> yyyy xxxx -(narrow)-> xxxx
                 // ==> no-op