[PATCH] D29153: [BranchFolding] Tail common all identical unreachable blocks

[Kyle Butt via Phabricator via llvm-commits]

iteratee added inline comments.


================
Comment at: lib/CodeGen/BranchFolding.cpp:521
+static bool blockEndsInUnreachable(const MachineBasicBlock *MBB) {
+  return MBB->succ_empty() && !MBB->isReturnBlock();
+}
----------------
rnk wrote:
> iteratee wrote:
> > Unforturnately there are platforms where this isn't sufficient. I believe ARM is one of them.
> For all the ARM examples I constructed, isReturnBlock appeared to be accurate.
OK, I have data.

isReturnBlock is currently insufficient for Thumb (That's why I thought ARM), Hexagon, Mips and XCore.
Arguably, this should go in anyway and those platforms should be fixed.

Funnily enough, this could cause switching away from Thumb to reduce code size.


https://reviews.llvm.org/D29153