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e6a65d5ecb
This trivially avoids violating the constant bus restriction. Previously this was allowing one SGPR in the first source operand, which technically also avoided violating this for most operations (but not for special cases reading vcc). We do need to write some new, smarter operand folds to pick the optimal SGPR to use in some kind of post-isel fold, but that's purely an optimization. I was originally thinking we would pick which operands should be SGPRs in RegBankSelect, but I think this isn't really manageable. There would be additional complexity to handle every G_* instruction, and then any nontrivial instruction patterns would need to know when to avoid violating it, which is likely to be very error prone. I think having all inputs being canonically copies to VGPRs will simplify the operand folding logic. The current folding we do is backwards, and only considers one operand at a time, relative to operands it already has. It therefore poorly handles the case where there is already a constant bus operand user. If all operands are copies, it's somewhat simpler to consider all input operands at once to choose the optimal constant bus user. Since the failure mode for constant bus violations is now a verifier error and not an selection failure, this moves towards a place where we can turn on the fallback mode. The SGPR copy folding optimizations can be left for later.
33 lines
959 B
YAML
33 lines
959 B
YAML
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
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# RUN: llc -march=amdgcn -mcpu=fiji -run-pass=regbankselect %s -verify-machineinstrs -o - -regbankselect-fast | FileCheck %s
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# RUN: llc -march=amdgcn -mcpu=fiji -run-pass=regbankselect %s -verify-machineinstrs -o - -regbankselect-greedy | FileCheck %s
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---
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name: fpext_s
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legalized: true
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body: |
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bb.0:
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liveins: $sgpr0
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; CHECK-LABEL: name: fpext_s
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; CHECK: [[COPY:%[0-9]+]]:sgpr(s32) = COPY $sgpr0
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; CHECK: [[COPY1:%[0-9]+]]:vgpr(s32) = COPY [[COPY]](s32)
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; CHECK: [[FPEXT:%[0-9]+]]:vgpr(s64) = G_FPEXT [[COPY1]](s32)
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%0:_(s32) = COPY $sgpr0
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%1:_(s64) = G_FPEXT %0
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...
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---
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name: fpext_v
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legalized: true
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body: |
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bb.0:
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liveins: $vgpr0
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; CHECK-LABEL: name: fpext_v
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; CHECK: [[COPY:%[0-9]+]]:vgpr(s32) = COPY $vgpr0
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; CHECK: [[FPEXT:%[0-9]+]]:vgpr(s64) = G_FPEXT [[COPY]](s32)
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%0:_(s32) = COPY $vgpr0
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%1:_(s64) = G_FPEXT %0
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...
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