[PATCH] D127831: BasicBlockUtils: Add a new way for CreateControlFlowHub()

Sameer Sahasrabuddhe via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Fri Oct 28 22:29:26 PDT 2022


sameerds added a comment.

In D127831#3891852 <https://reviews.llvm.org/D127831#3891852>, @foad wrote:

> Right, I understand that using an i32 instead of an i1 means that you need extra icmp instructions in the IR, but does it actually cause more instructions in the final generated code (for AMDGPU)? If the i1 was stored in a general purpose register then you would need a cmp //anyway// to use it to control a conditional branch.

I would expect that the i1 values get packed into an sreg, and then used in cbranch_vccz? That wouldn't need a cmp to actually compare the i1 value.


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