[PATCH] Add sign/zero extend to mips fast-isel

[Chad Rosier]

================
Comment at: lib/Target/Mips/MipsFastISel.cpp:251
@@ -243,1 +250,3 @@
 
+bool MipsFastISel::EmitIntSExt(MVT SrcVT, unsigned SrcReg, MVT DestVT,
+                               unsigned DestReg) {
----------------
Consider refactoring EmitIntSExt into a single function with a bool parameter, isSigned, that indicates if we're sign-extending or zero-extending.  I think as you continue to developer fast-isel you'll see a lot of redundancies between these functions.

================
Comment at: lib/Target/Mips/MipsFastISel.cpp:357
@@ +356,3 @@
+
+  unsigned SrcReg =
+      getRegForValue(Src); // his must be a 32 bit floating point register class
----------------
clang-format?

Comments should be complete sentences with proper punctuation.

================
Comment at: lib/Target/Mips/MipsFastISel.cpp:392
@@ +391,3 @@
+  if (isZExt) {
+    if (!EmitIntZExt(SrcVT, SrcReg, DestVT, ResultReg))
+      return false;
----------------
Pass isZExt as a parameter, per the suggestion above.  Logic will be simplified here as well.

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Comment at: lib/Target/Mips/MipsFastISel.cpp:411
@@ +410,3 @@
+
+  if (SrcVT != MVT::i32 && SrcVT != MVT::i16 && SrcVT != MVT::i8)
+    return false;
----------------
These are the correct type of checks, IMO.  It is much easier to understand when reviewing/refactoring.

http://reviews.llvm.org/D4827