From 9f96e589c94cdf6d275a2bfebc0202017acd0369 Mon Sep 17 00:00:00 2001
From: Dan Gohman <sunfish@google.com>
Date: Wed, 4 Sep 2013 21:16:07 -0700
Subject: [PATCH] Bug 885169 - Spidermonkey: Alleviate register allocation
 constraints in ICGetElem_Arguments::Compiler::generateStubCode. r=nbp

---
 js/src/jit/BaselineIC.cpp           |  3 ++-
 js/src/jit/arm/MacroAssembler-arm.h | 30 +++++++++++++++++++++++------
 js/src/jit/x86/MacroAssembler-x86.h | 26 +++++++++++++++++++------
 3 files changed, 46 insertions(+), 13 deletions(-)

diff --git a/js/src/jit/BaselineIC.cpp b/js/src/jit/BaselineIC.cpp
index ca883d1c2bba..bdfb5e857952 100644
--- a/js/src/jit/BaselineIC.cpp
+++ b/js/src/jit/BaselineIC.cpp
@@ -3970,7 +3970,7 @@ ICGetElem_Arguments::Compiler::generateStubCode(MacroAssembler &masm)
     regs = availableGeneralRegs(0);
     regs.takeUnchecked(objReg);
     regs.takeUnchecked(idxReg);
-    regs.takeUnchecked(scratchReg);
+    regs.take(scratchReg);
     Register argData = regs.takeAny();
     Register tempReg = regs.takeAny();
 
@@ -3992,6 +3992,7 @@ ICGetElem_Arguments::Compiler::generateStubCode(MacroAssembler &masm)
     masm.addPtr(Imm32(ArgumentsData::offsetOfArgs()), argData);
     regs.add(scratchReg);
     regs.add(tempReg);
+    regs.add(argData);
     ValueOperand tempVal = regs.takeAnyValue();
     masm.loadValue(BaseIndex(argData, idxReg, ScaleFromElemWidth(sizeof(Value))), tempVal);
 
diff --git a/js/src/jit/arm/MacroAssembler-arm.h b/js/src/jit/arm/MacroAssembler-arm.h
index 5c8e52159d48..5cd54627f98b 100644
--- a/js/src/jit/arm/MacroAssembler-arm.h
+++ b/js/src/jit/arm/MacroAssembler-arm.h
@@ -954,12 +954,30 @@ class MacroAssemblerARMCompat : public MacroAssemblerARM
     void moveValue(const Value &val, const ValueOperand &dest);
 
     void moveValue(const ValueOperand &src, const ValueOperand &dest) {
-        JS_ASSERT(src.typeReg() != dest.payloadReg());
-        JS_ASSERT(src.payloadReg() != dest.typeReg());
-        if (src.typeReg() != dest.typeReg())
-            ma_mov(src.typeReg(), dest.typeReg());
-        if (src.payloadReg() != dest.payloadReg())
-            ma_mov(src.payloadReg(), dest.payloadReg());
+        Register s0 = src.typeReg(), d0 = dest.typeReg(),
+                 s1 = src.payloadReg(), d1 = dest.payloadReg();
+
+        // Either one or both of the source registers could be the same as a
+        // destination register.
+        if (s1 == d0) {
+            if (s0 == d1) {
+                // If both are, this is just a swap of two registers.
+                JS_ASSERT(d1 != ScratchRegister);
+                JS_ASSERT(d0 != ScratchRegister);
+                ma_mov(d1, ScratchRegister);
+                ma_mov(d0, d1);
+                ma_mov(ScratchRegister, d0);
+                return;
+            }
+            // If only one is, copy that source first.
+            mozilla::Swap(s0, s1);
+            mozilla::Swap(d0, d1);
+        }
+
+        if (s0 != d0)
+            ma_mov(s0, d0);
+        if (s1 != d1)
+            ma_mov(s1, d1);
     }
 
     void storeValue(ValueOperand val, Operand dst);
diff --git a/js/src/jit/x86/MacroAssembler-x86.h b/js/src/jit/x86/MacroAssembler-x86.h
index 5b3d579562fa..dcb8673f5fb9 100644
--- a/js/src/jit/x86/MacroAssembler-x86.h
+++ b/js/src/jit/x86/MacroAssembler-x86.h
@@ -113,12 +113,26 @@ class MacroAssemblerX86 : public MacroAssemblerX86Shared
         moveValue(val, dest.typeReg(), dest.payloadReg());
     }
     void moveValue(const ValueOperand &src, const ValueOperand &dest) {
-        JS_ASSERT(src.typeReg() != dest.payloadReg());
-        JS_ASSERT(src.payloadReg() != dest.typeReg());
-        if (src.typeReg() != dest.typeReg())
-            movl(src.typeReg(), dest.typeReg());
-        if (src.payloadReg() != dest.payloadReg())
-            movl(src.payloadReg(), dest.payloadReg());
+        Register s0 = src.typeReg(), d0 = dest.typeReg(),
+                 s1 = src.payloadReg(), d1 = dest.payloadReg();
+
+        // Either one or both of the source registers could be the same as a
+        // destination register.
+        if (s1 == d0) {
+            if (s0 == d1) {
+                // If both are, this is just a swap of two registers.
+                xchgl(d0, d1);
+                return;
+            }
+            // If only one is, copy that source first.
+            mozilla::Swap(s0, s1);
+            mozilla::Swap(d0, d1);
+        }
+
+        if (s0 != d0)
+            movl(s0, d0);
+        if (s1 != d1)
+            movl(s1, d1);
     }
 
     /////////////////////////////////////////////////////////////////