Skip back edge creation for "do ... while(false)" loops

Drive-by fix: Fix disassembling "prefetch" instruction on ia32

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/131733002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18519 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 69969bd..929133b 100644 (file)
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -4336,12 +4336,17 @@ void HOptimizedGraphBuilder::VisitDoWhileStatement(DoWhileStatement* stmt) {
   HBasicBlock* loop_successor = NULL;
   if (body_exit != NULL && !stmt->cond()->ToBooleanIsTrue()) {
     set_current_block(body_exit);
-    // The block for a true condition, the actual predecessor block of the
-    // back edge.
-    body_exit = graph()->CreateBasicBlock();
     loop_successor = graph()->CreateBasicBlock();
-    CHECK_BAILOUT(VisitForControl(stmt->cond(), body_exit, loop_successor));
-    if (body_exit->HasPredecessor()) {
+    if (stmt->cond()->ToBooleanIsFalse()) {
+      Goto(loop_successor);
+      body_exit = NULL;
+    } else {
+      // The block for a true condition, the actual predecessor block of the
+      // back edge.
+      body_exit = graph()->CreateBasicBlock();
+      CHECK_BAILOUT(VisitForControl(stmt->cond(), body_exit, loop_successor));
+    }
+    if (body_exit != NULL && body_exit->HasPredecessor()) {
       body_exit->SetJoinId(stmt->BackEdgeId());
     } else {
       body_exit = NULL;

diff --git a/src/ia32/disasm-ia32.cc b/src/ia32/disasm-ia32.cc
index 057a558..6a7f3bc 100644 (file)
--- a/src/ia32/disasm-ia32.cc
+++ b/src/ia32/disasm-ia32.cc
@@ -1007,6 +1007,7 @@ int DisassemblerIA32::InstructionDecode(v8::internal::Vector<char> out_buffer,
         { byte f0byte = data[1];
           const char* f0mnem = F0Mnem(f0byte);
           if (f0byte == 0x18) {
+            data += 2;
             int mod, regop, rm;
             get_modrm(*data, &mod, &regop, &rm);
             const char* suffix[] = {"nta", "1", "2", "3"};