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Add algebraic simplifications to get rid of 1-based index IR bloat #156

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Merged
maleadt merged 4 commits into from
Mar 30, 2026
Merged

Add algebraic simplifications to get rid of 1-based index IR bloat #156

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c9345f7
Add algebraic simplification pass to cancel addi/subi pairs.
maleadt Mar 30, 2026
01146a5
Worklist-based fixpoint rewrite driver.
maleadt Mar 30, 2026
c4e0b0b
Use IRStructurizer's users() API in rewrite driver.
maleadt Mar 30, 2026
c11c65d
Use SSAValue consistently instead of bare Int for SSA indices.
maleadt Mar 30, 2026
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31 changes: 27 additions & 4 deletions src/compiler/codegen/passes/pipeline.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -111,6 +111,31 @@ const FMA_RULES = RewriteRule[

fma_fusion_pass!(sci::StructuredIRCode) = rewrite_patterns!(sci, FMA_RULES)

#=============================================================================
Algebraic Simplification (rewrite)
=============================================================================#

# Cancel inverse addi/subi pairs: x+c-c → x, x-c+c → x.
# Repeated ~c binds enforce that both operands are the same value.

const ALGEBRA_RULES = RewriteRule[
@rewrite Intrinsics.subi(Intrinsics.addi(~x, ~c), ~c) => ~x
@rewrite Intrinsics.addi(Intrinsics.subi(~x, ~c), ~c) => ~x
]

algebra_pass!(sci::StructuredIRCode) = rewrite_patterns!(sci, ALGEBRA_RULES)

#=============================================================================
Combined Rule Set
=============================================================================#

const ALL_REWRITE_RULES = RewriteRule[
NORMALIZE_RULES...,
ALGEBRA_RULES...,
SVE_RULES...,
FMA_RULES...,
]

#=============================================================================
Pass Pipeline
=============================================================================#
Expand All @@ -122,10 +147,8 @@ Run the full pass pipeline on a StructuredIRCode. Called for both kernel
and subprogram compilation.
"""
function run_passes!(sci::StructuredIRCode)
# Rewrite passes (order matters: normalize before optimize, SVE before FMA)
normalize_pass!(sci)
scalar_view_elim_pass!(sci)
fma_fusion_pass!(sci)
# All rewrite rules in one fixpoint pass
rewrite_patterns!(sci, ALL_REWRITE_RULES)

# Memory ordering
alias_result = alias_analysis_pass!(sci)
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