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diff src/share/vm/opto/mulnode.cpp @ 6891:67f4c477c9ab

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8000805: JMM issue: short loads are non-atomic Summary: perform transforms during IGVN phase when Load has a single user. Reviewed-by: jrose, kvn, twisti
author vlivanov
date Mon, 22 Oct 2012 11:44:30 -0700
parents d804e148cff8
children 2113136690bc
line wrap: on
line diff
--- a/src/share/vm/opto/mulnode.cpp	Fri Oct 19 14:21:09 2012 -0400
+++ b/src/share/vm/opto/mulnode.cpp	Mon Oct 22 11:44:30 2012 -0700
@@ -479,24 +479,27 @@
     return new (phase->C) AndINode(load,phase->intcon(mask&0xFFFF));
 
   // Masking bits off of a Short?  Loading a Character does some masking
-  if (lop == Op_LoadS && (mask & 0xFFFF0000) == 0 ) {
-    Node *ldus = new (phase->C) LoadUSNode(load->in(MemNode::Control),
-                                              load->in(MemNode::Memory),
-                                              load->in(MemNode::Address),
-                                              load->adr_type());
-    ldus = phase->transform(ldus);
-    return new (phase->C) AndINode(ldus, phase->intcon(mask & 0xFFFF));
-  }
+  if (can_reshape &&
+      load->outcnt() == 1 && load->unique_out() == this) {
+    if (lop == Op_LoadS && (mask & 0xFFFF0000) == 0 ) {
+      Node *ldus = new (phase->C) LoadUSNode(load->in(MemNode::Control),
+                                             load->in(MemNode::Memory),
+                                             load->in(MemNode::Address),
+                                             load->adr_type());
+      ldus = phase->transform(ldus);
+      return new (phase->C) AndINode(ldus, phase->intcon(mask & 0xFFFF));
+    }
 
-  // Masking sign bits off of a Byte?  Do an unsigned byte load plus
-  // an and.
-  if (lop == Op_LoadB && (mask & 0xFFFFFF00) == 0) {
-    Node* ldub = new (phase->C) LoadUBNode(load->in(MemNode::Control),
-                                              load->in(MemNode::Memory),
-                                              load->in(MemNode::Address),
-                                              load->adr_type());
-    ldub = phase->transform(ldub);
-    return new (phase->C) AndINode(ldub, phase->intcon(mask));
+    // Masking sign bits off of a Byte?  Do an unsigned byte load plus
+    // an and.
+    if (lop == Op_LoadB && (mask & 0xFFFFFF00) == 0) {
+      Node* ldub = new (phase->C) LoadUBNode(load->in(MemNode::Control),
+                                             load->in(MemNode::Memory),
+                                             load->in(MemNode::Address),
+                                             load->adr_type());
+      ldub = phase->transform(ldub);
+      return new (phase->C) AndINode(ldub, phase->intcon(mask));
+    }
   }
 
   // Masking off sign bits?  Dont make them!
@@ -923,7 +926,9 @@
       set_req(2, phase->intcon(0));
       return this;
     }
-    else if( ld->Opcode() == Op_LoadUS )
+    else if( can_reshape &&
+             ld->Opcode() == Op_LoadUS &&
+             ld->outcnt() == 1 && ld->unique_out() == shl)
       // Replace zero-extension-load with sign-extension-load
       return new (phase->C) LoadSNode( ld->in(MemNode::Control),
                                 ld->in(MemNode::Memory),