[PATCH] D29344: [AArch64] Extend redundant copy elimination pass to handle non-zero stores.

[Jun Bum Lim via Phabricator via llvm-commits]

junbuml added a comment.

LGTM



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Comment at: lib/Target/AArch64/AArch64RedundantCopyElimination.cpp:115
+/// branch \p CondBr jumps and whos equality comparison is against a constant.
+/// If true, return the compare instruction the branch is predicated upon.
+/// Otherwise, return nullptr.
----------------
This return the compare instruction  the branch is predicated upon. 


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Comment at: lib/Target/AArch64/AArch64RedundantCopyElimination.cpp:214
+    --Itr;
+    dbgs() << "Itr: " << *Itr << '\n';
+    if (guaranteesZeroRegInBlock(*Itr, MBB)) {
----------------
Please remove it.


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Comment at: lib/Target/AArch64/AArch64RedundantCopyElimination.cpp:215-226
+    if (guaranteesZeroRegInBlock(*Itr, MBB)) {
+      // Itr is a CBZ/CBNZ in this context.
+      MCPhysReg KnownReg = Itr->getOperand(0).getReg();
+      KnownRegs.push_back(RegImm(KnownReg, 0));
+      FirstUse = Itr;
+    } else if (MachineInstr *Cmp = knownRegValInBlock(*Itr, MBB)) {
+      // Itr is a conditional branch (i.e., Bcc) and Cmp is a compare
----------------
Isn't it possible to merge the "if" and "else if" block as these two block do almost the same thing ? Maybe move guaranteesZeroRegInBlock() in knownRegValInBlock() ?


https://reviews.llvm.org/D29344