[PATCH] [Thumb1] Re-write emitThumbRegPlusImmediate

[Oliver Stannard]

================
Comment at: lib/Target/ARM/Thumb1RegisterInfo.cpp:250-253
@@ +249,6 @@
+  unsigned RequiredCopyInstrs = CopyOpc ? 1 : 0;
+  unsigned RangeAfterCopy = (CopyRange > Bytes) ? 0 : (Bytes - CopyRange);
+  unsigned RequiredExtraInstrs;
+  if (ExtraRange)
+    RequiredExtraInstrs = RoundUpToOddAlignment(RangeAfterCopy, ExtraRange) / ExtraRange;
+  else
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t.p.northover wrote:
> This doesn't seem to line up with what actually gets implemented. In particular, I think we're in deep trouble if the RangeAfterCopy actually does get rounded up.
I'm not sure I follow. This should round RequiredExtraInstrs up to the lowest integer number of instructions that could be used, and the loop then handles as much of the immediate as possible with each instruction, so these should match up. Can you give an example where this doesn't work?

http://reviews.llvm.org/D6211