From 44f7bd9fe0e65b9620c1258db25a19d5b0d9e987 Mon Sep 17 00:00:00 2001
From: Joel Dice <joel.dice@gmail.com>
Date: Wed, 10 Aug 2011 21:33:56 -0600
Subject: [PATCH] fix argument alignment for Darwin/ARM

---
 src/arm.cpp      | 12 ++++++++++++
 src/arm.h        | 20 ++++++++++++++------
 src/assembler.h  |  1 +
 src/compiler.cpp | 18 ++++++++----------
 src/powerpc.cpp  |  4 ++++
 src/x86.cpp      |  4 ++++
 6 files changed, 43 insertions(+), 16 deletions(-)

diff --git a/src/arm.cpp b/src/arm.cpp
index e23ad3cfd1..f7a50b815a 100644
--- a/src/arm.cpp
+++ b/src/arm.cpp
@@ -1834,7 +1834,19 @@ class MyArchitecture: public Assembler::Architecture {
   }
 
   virtual bool argumentAlignment() {
+#ifdef __APPLE__
+    return false;
+#else
     return true;
+#endif
+  }
+
+  virtual bool argumentRegisterAlignment() {
+#ifdef __APPLE__
+    return false;
+#else
+    return true;
+#endif
   }
 
   virtual unsigned argumentRegisterCount() {
diff --git a/src/arm.h b/src/arm.h
index ab97c88767..a5285f86c3 100644
--- a/src/arm.h
+++ b/src/arm.h
@@ -128,6 +128,12 @@ dynamicCall(void* function, uintptr_t* arguments, uint8_t* argumentTypes,
             unsigned argumentCount, unsigned argumentsSize UNUSED,
             unsigned returnType UNUSED)
 {
+#ifdef __APPLE__
+  const unsigned Alignment = 1;
+#else
+  const unsigned Alignment = 2;
+#endif
+
   const unsigned GprCount = 4;
   uintptr_t gprTable[GprCount];
   unsigned gprIndex = 0;
@@ -140,19 +146,21 @@ dynamicCall(void* function, uintptr_t* arguments, uint8_t* argumentTypes,
     switch (argumentTypes[ati]) {
     case DOUBLE_TYPE:
     case INT64_TYPE: {
-      if (gprIndex + (8 / BytesPerWord) <= GprCount) { // pass argument on registers
-        if (gprIndex & 1) {                            // 8-byte alignment
-          memset(gprTable + gprIndex, 0, 4);           // probably not necessary, but for good luck
+      if (gprIndex + Alignment <= GprCount) { // pass argument on registers
+        if (gprIndex % Alignment) {           // 8-byte alignment
+          memset(gprTable + gprIndex, 0, 4);  // probably not necessary, but for good luck
           ++gprIndex;
         }
+
         memcpy(gprTable + gprIndex, arguments + ai, 8);
         gprIndex += 8 / BytesPerWord;
-      } else {                                         // pass argument on stack
+      } else {                                // pass argument on stack
         gprIndex = GprCount;
-        if (stackIndex & 1) {                          // 8-byte alignment
-          memset(stack + stackIndex, 0, 4);            // probably not necessary, but for good luck
+        if (stackIndex % Alignment) {         // 8-byte alignment
+          memset(stack + stackIndex, 0, 4);   // probably not necessary, but for good luck
           ++stackIndex;
         }
+
         memcpy(stack + stackIndex, arguments + ai, 8);
         stackIndex += 8 / BytesPerWord;
       }
diff --git a/src/assembler.h b/src/assembler.h
index 4107d19854..4805f54e80 100644
--- a/src/assembler.h
+++ b/src/assembler.h
@@ -330,6 +330,7 @@ class Assembler {
     virtual unsigned frameFootprint(unsigned footprint) = 0;
     virtual unsigned argumentFootprint(unsigned footprint) = 0;
     virtual bool argumentAlignment() = 0;
+    virtual bool argumentRegisterAlignment() = 0;
     virtual unsigned argumentRegisterCount() = 0;
     virtual int argumentRegister(unsigned index) = 0;
 
diff --git a/src/compiler.cpp b/src/compiler.cpp
index a81d597beb..0b7e8d1917 100644
--- a/src/compiler.cpp
+++ b/src/compiler.cpp
@@ -3179,21 +3179,19 @@ class CallEvent: public Event {
       unsigned argumentIndex = 0;
 
       while (true) {
-        unsigned footprint;
-        if (argumentIndex + 1 < argumentCount
-            and s->value->nextWord == s->next->value)
-        {
-          footprint = 2;
-        } else {
-          footprint = 1;
-        }
+        unsigned footprint
+          = (argumentIndex + 1 < argumentCount
+             and s->value->nextWord == s->next->value)
+          ? 2 : 1;
 
-        if (footprint > 1 and index & 1 and c->arch->argumentAlignment()) {
+        if (index % (c->arch->argumentAlignment() ? footprint : 1)) {
           ++ index;
         }
 
         SiteMask targetMask;
-        if (index + footprint <= c->arch->argumentRegisterCount()) {
+        if (index + (c->arch->argumentRegisterAlignment() ? footprint : 1)
+            <= c->arch->argumentRegisterCount())
+        {
           int number = c->arch->argumentRegister(index);
         
           if (DebugReads) {
diff --git a/src/powerpc.cpp b/src/powerpc.cpp
index 67a223e46a..f518dea650 100644
--- a/src/powerpc.cpp
+++ b/src/powerpc.cpp
@@ -2135,6 +2135,10 @@ class MyArchitecture: public Assembler::Architecture {
     return AlignArguments;
   }
 
+  virtual bool argumentRegisterAlignment() {
+    return true;
+  }
+
   virtual unsigned argumentRegisterCount() {
     return 8;
   }
diff --git a/src/x86.cpp b/src/x86.cpp
index 6c4fe1f21b..670c5482d3 100644
--- a/src/x86.cpp
+++ b/src/x86.cpp
@@ -2824,6 +2824,10 @@ class MyArchitecture: public Assembler::Architecture {
     return false;
   }
 
+  virtual bool argumentRegisterAlignment() {
+    return false;
+  }
+
   virtual unsigned argumentRegisterCount() {
 #ifdef PLATFORM_WINDOWS
     if (BytesPerWord == 8) return 4; else