[PATCH] Synchronize the NaCl DataLayout string with the one in clang

[Derek Schuff]

  Thanks for looking at this.
  Just to refresh my memory, the preferred alignment defaults to the ABI alignment, so e.g. i64:64:64 is equivalent to i64:64, correct?


================
Comment at: lib/Target/ARM/ARMTargetMachine.cpp:93
@@ +92,3 @@
+  if (ST.isTargetNaCl())
+    Ret += "-v128:32";
+  else if (ST.isAPCS_ABI())
----------------
NaCl uses AAPCS VFP conventions, with a stack alignment of 16 bytes. Would it make more sense just to set that in ARMSubtarget.cpp instead of special casing here?


================
Comment at: lib/Target/X86/X86TargetMachine.cpp:43
@@ -43,1 +42,3 @@
+  if (ST.is64Bit() || ST.isTargetCygMing() || ST.isTargetWindows() ||
+      ST.isTargetNaCl())
     Ret += "-i64:64";
----------------
I'm a little unclear about this; does this mean 64-bit targets have i64 but not f64?
NaCl does use f64:64 and i64:64 for both 32 and 64 bits, but I don't see where else but here that f64 is even set.

================
Comment at: lib/Target/X86/X86TargetMachine.cpp:56
@@ -52,16 +55,3 @@
 
-  // Objects on the stack ore aligned to 64 bits.
-  if (ST.is64Bit())
-    Ret += "-s:64";
-
-  // The registers can hold 8, 16, 32 or, in x86-64, 64 bits.
-  if (ST.is64Bit())
-    Ret += "-n8:16:32:64";
-  else
-    Ret += "-n8:16:32";
-
-  // The stack is aligned to 32 bits on some ABIs and 128 bits on others.
-  if (!ST.is64Bit() && (ST.isTargetCygMing() || ST.isTargetWindows()))
-    Ret += "-S32";
-  else
-    Ret += "-S128";
+  if (ST.isTargetNaCl())
+    Ret += "-v128:32";
----------------
This can be removed. Clang seems to have it it upstream, but that's wrong. vectors are never generated for le32, and for i686-nacl and x86_64-nacl they have the same alignment as linux.

================
Comment at: lib/Target/X86/X86TargetMachine.cpp:59
@@ +58,3 @@
+
+  if (!ST.isTargetNaCl()) {
+    // Objects on the stack ore aligned to 64 bits.
----------------
I think this condition can move to just the stack alignment, as we use s32-n8:16:32-S128 for i686-nacl and s:64-n8:16:32:64-S128 for x86_64-nacl


http://llvm-reviews.chandlerc.com/D2436