[PATCH] D129735: [RISCV] Add new pass to transform undef to pseudo for vector values.

[Craig Topper via Phabricator via llvm-commits]

craig.topper accepted this revision.
craig.topper added a comment.
This revision is now accepted and ready to land.

LGTM



================
Comment at: llvm/lib/Target/RISCV/RISCVRVVInitUndef.cpp:151
+    bool TiedToDef = false;
+    for (MachineOperand &UseMO : UserMI->operands()) {
+      if (!UseMO.isReg())
----------------
BeMg wrote:
> craig.topper wrote:
> > Do we need to scan all operands? Can we check if MO is a tied use and find the operand it is tied to check the early clobber?
> ```
> 0B      bb.0.entry:
> 16B       LIFETIME_START %stack.0.dst
> 32B       %1:vr = IMPLICIT_DEF
> 48B       early-clobber %0:vr = PseudoVRGATHER_VI_M1 killed %1:vr, 0, 0, 5
> 64B       %2:gpr = ADDI %stack.0.dst, 0
> 80B       PseudoVSE32_V_M1 killed %0:vr, killed %2:gpr, 0, 5
> 96B       LIFETIME_END %stack.0.dst
> 112B      %3:gpr = COPY $x0
> 128B      $x10 = COPY %3:gpr
> 144B      PseudoRET implicit $x10
> ```
> 
> Here we maybe need scan both defs and uses operand, because the early-clobber operand not always exist tied-to operand.
Right. I wasn't thinking about that right.


Repository:
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  https://reviews.llvm.org/D129735/new/

https://reviews.llvm.org/D129735