From 497cb2e84ebc88aa65d5fe877d1e7597ce50c262 Mon Sep 17 00:00:00 2001
From: Boris Zbarsky <bzbarsky@mit.edu>
Date: Fri, 28 Dec 2012 12:40:45 -0800
Subject: [PATCH] Bug 817943 part 2.  Make the x86-64 and ARM versions of
 passABIArg not generate no-op moves and add asserts to the moveResolver that
 there are no such moves.  r=pierron,mjrosenberg

---
 js/src/ion/MoveResolver.cpp           |  2 ++
 js/src/ion/arm/MacroAssembler-arm.cpp | 14 ++++++++++----
 js/src/ion/x64/MacroAssembler-x64.cpp |  8 ++++++++
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/js/src/ion/MoveResolver.cpp b/js/src/ion/MoveResolver.cpp
index 9fe067d0701..01fb6e3384e 100644
--- a/js/src/ion/MoveResolver.cpp
+++ b/js/src/ion/MoveResolver.cpp
@@ -24,6 +24,8 @@ MoveResolver::resetState()
 bool
 MoveResolver::addMove(const MoveOperand &from, const MoveOperand &to, Move::Kind kind)
 {
+    // Assert that we're not doing no-op moves.
+    JS_ASSERT(!(from == to));
     PendingMove *pm = movePool_.allocate();
     if (!pm)
         return false;
diff --git a/js/src/ion/arm/MacroAssembler-arm.cpp b/js/src/ion/arm/MacroAssembler-arm.cpp
index 94de77cbb4f..ca4ed6e5d7d 100644
--- a/js/src/ion/arm/MacroAssembler-arm.cpp
+++ b/js/src/ion/arm/MacroAssembler-arm.cpp
@@ -2708,10 +2708,13 @@ MacroAssemblerARMCompat::passABIArg(const MoveOperand &from)
     if (from.isDouble()) {
         FloatRegister fr;
         if (GetFloatArgReg(usedIntSlots_, usedFloatSlots_, &fr)) {
-            enoughMemory_ = moveResolver_.addMove(from, MoveOperand(fr), Move::DOUBLE);
+            if (!from.isFloatReg() || from.floatReg() != fr) {
+                enoughMemory_ = moveResolver_.addMove(from, MoveOperand(fr), Move::DOUBLE);
+            }
+            // else nothing to do; the value is in the right register already
         } else {
             // If (and only if) the integer registers have started spilling, do we
-            // need to take the double register's alignment into accoun
+            // need to take the double register's alignment into account
             uint32_t disp = GetFloatArgStackDisp(usedIntSlots_, usedFloatSlots_, &padding_);
             enoughMemory_ = moveResolver_.addMove(from, MoveOperand(sp, disp), Move::DOUBLE);
         }
@@ -2719,13 +2722,16 @@ MacroAssemblerARMCompat::passABIArg(const MoveOperand &from)
     } else {
         Register r;
         if (GetIntArgReg(usedIntSlots_, usedFloatSlots_, &r)) {
-            enoughMemory_ = moveResolver_.addMove(from, MoveOperand(r), Move::GENERAL);
+            if (!from.isGeneralReg() || from.reg() != r) {
+                enoughMemory_ = moveResolver_.addMove(from, MoveOperand(r), Move::GENERAL);
+            }
+            // else nothing to do; the value is in the right register already
         } else {
             uint32_t disp = GetIntArgStackDisp(usedIntSlots_, usedFloatSlots_, &padding_);
             fprintf(stderr, "Float on the stack! (%d)\n", disp);
             enoughMemory_ = moveResolver_.addMove(from, MoveOperand(sp, disp), Move::GENERAL);
         }
-            usedIntSlots_++;
+        usedIntSlots_++;
     }
 
 }
diff --git a/js/src/ion/x64/MacroAssembler-x64.cpp b/js/src/ion/x64/MacroAssembler-x64.cpp
index 36b6b76aa7f..2000dcfa94b 100644
--- a/js/src/ion/x64/MacroAssembler-x64.cpp
+++ b/js/src/ion/x64/MacroAssembler-x64.cpp
@@ -51,6 +51,10 @@ MacroAssemblerX64::passABIArg(const MoveOperand &from)
     if (from.isDouble()) {
         FloatRegister dest;
         if (GetFloatArgReg(passedIntArgs_, passedFloatArgs_++, &dest)) {
+            if (from.isFloatReg() && from.floatReg() == dest) {
+                // Nothing to do; the value is in the right register already
+                return;
+            }
             to = MoveOperand(dest);
         } else {
             to = MoveOperand(StackPointer, stackForCall_);
@@ -60,6 +64,10 @@ MacroAssemblerX64::passABIArg(const MoveOperand &from)
     } else {
         Register dest;
         if (GetIntArgReg(passedIntArgs_++, passedFloatArgs_, &dest)) {
+            if (from.isGeneralReg() && from.reg() == dest) {
+                // Nothing to do; the value is in the right register already
+                return;
+            }
             to = MoveOperand(dest);
         } else {
             to = MoveOperand(StackPointer, stackForCall_);