[PATCH] D10826: Fix AArch64 prologue for empty frame with dynamic allocas

[Kristof Beyls]

kristof.beyls added a comment.

I've only got two very minor suggestions for improvements.
With those improvements, LGTM!


================
Comment at: lib/Target/AArch64/AArch64FrameLowering.cpp:354-356
@@ -353,7 +353,5 @@
   unsigned scratchSPReg = AArch64::SP;
-  if (NeedsRealignment) {
-    // Use the first callee-saved register as a scratch register
-    assert(MF.getRegInfo().isPhysRegUsed(AArch64::X9) &&
-           "No scratch register to align SP!");
+  if (NumBytes && NeedsRealignment) {
     scratchSPReg = AArch64::X9;
+    MF.getRegInfo().setPhysRegUsed(scratchSPReg);
   }
----------------
I'd keep the comment
  // Use the first callee-saved register as a scratch register
otherwise looks ok.

================
Comment at: test/CodeGen/AArch64/aarch64-dynamic-stack-layout.ll:525-526
@@ +524,4 @@
+; Extra realignment in the prologue (performance issue).
+; X19 is used as a scratch register for SP realignment before it is assigned the
+; base pointer.
+; CHECK:  sub  x9, sp, #32            // =32
----------------
This comment isn't correct anymore in the newest version of the patch. I would just remove the comment.


http://reviews.llvm.org/D10826