JIT: Improve BBJ_COND to BBJ_ALWAYS conversion in fgUpdateFlowGraph #97681
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch Issue DetailsFollow-up to #97488. In
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Diff results for #97681Throughput diffsThroughput diffs for linux/arm64 ran on windows/x64Overall (+0.02% to +0.06%)
FullOpts (+0.03% to +0.07%)
Throughput diffs for linux/x64 ran on windows/x64Overall (+0.02% to +0.07%)
FullOpts (+0.04% to +0.08%)
Throughput diffs for osx/arm64 ran on windows/x64Overall (+0.02% to +0.06%)
FullOpts (+0.03% to +0.06%)
Throughput diffs for windows/arm64 ran on windows/x64Overall (+0.02% to +0.06%)
MinOpts (-0.00% to +0.01%)
FullOpts (+0.03% to +0.06%)
Throughput diffs for windows/x64 ran on windows/x64Overall (+0.02% to +0.06%)
FullOpts (+0.04% to +0.06%)
Details here |
Diff results for #97681Assembly diffsAssembly diffs for linux/arm64 ran on windows/x64Diffs are based on 2,259,470 contexts (1,008,044 MinOpts, 1,251,426 FullOpts). MISSED contexts: 159 (0.01%) Overall (-42,568 bytes)
FullOpts (-42,568 bytes)
Assembly diffs for linux/x64 ran on windows/x64Diffs are based on 2,249,703 contexts (981,298 MinOpts, 1,268,405 FullOpts). MISSED contexts: 134 (0.01%) Overall (-47,589 bytes)
FullOpts (-47,589 bytes)
Assembly diffs for windows/x64 ran on windows/x64Diffs are based on 2,098,526 contexts (926,221 MinOpts, 1,172,305 FullOpts). MISSED contexts: 138 (0.01%) Overall (-41,586 bytes)
FullOpts (-41,586 bytes)
Details here Assembly diffs for windows/x86 ran on windows/x86Diffs are based on 2,290,721 contexts (838,165 MinOpts, 1,452,556 FullOpts). MISSED contexts: base: 808 (0.04%), diff: 842 (0.04%) Overall (-20,881 bytes)
FullOpts (-20,881 bytes)
Details here Throughput diffsThroughput diffs for linux/arm ran on windows/x86Overall (+0.01% to +0.03%)
FullOpts (+0.01% to +0.04%)
Throughput diffs for windows/x86 ran on windows/x86Overall (+0.02% to +0.06%)
FullOpts (+0.03% to +0.06%)
Details here Throughput diffs for linux/arm64 ran on linux/x64Overall (+0.02% to +0.07%)
FullOpts (+0.03% to +0.08%)
Throughput diffs for linux/x64 ran on linux/x64Overall (+0.02% to +0.08%)
FullOpts (+0.04% to +0.09%)
Details here |
Diff results for #97681Assembly diffsAssembly diffs for windows/x64 ran on linux/x64Diffs are based on 2,512,204 contexts (997,391 MinOpts, 1,514,813 FullOpts). MISSED contexts: 8 (0.00%) Overall (-52,115 bytes)
FullOpts (-52,115 bytes)
Details here Throughput diffsThroughput diffs for linux/arm64 ran on windows/x64Overall (+0.02% to +0.06%)
FullOpts (+0.03% to +0.07%)
Throughput diffs for linux/x64 ran on windows/x64Overall (+0.02% to +0.07%)
FullOpts (+0.04% to +0.08%)
Throughput diffs for osx/arm64 ran on windows/x64Overall (+0.02% to +0.06%)
FullOpts (+0.03% to +0.06%)
Throughput diffs for windows/arm64 ran on windows/x64Overall (+0.02% to +0.06%)
MinOpts (-0.01% to +0.00%)
FullOpts (+0.03% to +0.06%)
Throughput diffs for windows/x64 ran on windows/x64Overall (+0.02% to +0.07%)
FullOpts (+0.03% to +0.07%)
Details here Throughput diffs for windows/x86 ran on linux/x86Overall (+0.02% to +0.06%)
FullOpts (+0.03% to +0.06%)
Details here |
Diff results for #97681Assembly diffsAssembly diffs for linux/x64 ran on windows/x64Diffs are based on 2,517,901 contexts (991,070 MinOpts, 1,526,831 FullOpts). MISSED contexts: 8 (0.00%) Overall (-50,401 bytes)
FullOpts (-50,401 bytes)
Assembly diffs for windows/x64 ran on windows/x64Diffs are based on 2,512,204 contexts (997,391 MinOpts, 1,514,813 FullOpts). MISSED contexts: 8 (0.00%) Overall (-52,115 bytes)
FullOpts (-52,115 bytes)
Details here Assembly diffs for windows/x86 ran on windows/x86Diffs are based on 2,293,423 contexts (839,658 MinOpts, 1,453,765 FullOpts). MISSED contexts: base: 38 (0.00%), diff: 73 (0.00%) Overall (-22,900 bytes)
FullOpts (-22,900 bytes)
Details here Throughput diffsThroughput diffs for linux/arm64 ran on windows/x64Overall (+0.02% to +0.06%)
FullOpts (+0.03% to +0.07%)
Throughput diffs for linux/x64 ran on windows/x64Overall (+0.02% to +0.07%)
FullOpts (+0.04% to +0.08%)
Throughput diffs for osx/arm64 ran on windows/x64Overall (+0.02% to +0.06%)
FullOpts (+0.03% to +0.06%)
Throughput diffs for windows/arm64 ran on windows/x64Overall (+0.02% to +0.06%)
MinOpts (-0.01% to +0.00%)
FullOpts (+0.03% to +0.06%)
Throughput diffs for windows/x64 ran on windows/x64Overall (+0.02% to +0.07%)
FullOpts (+0.03% to +0.07%)
Details here Throughput diffs for linux/arm ran on windows/x86Overall (+0.01% to +0.04%)
FullOpts (+0.01% to +0.04%)
Throughput diffs for windows/x86 ran on windows/x86Overall (+0.02% to +0.06%)
FullOpts (+0.03% to +0.06%)
Details here Throughput diffs for linux/arm64 ran on linux/x64Overall (-0.14% to +0.00%)
FullOpts (-0.16% to +0.00%)
Throughput diffs for linux/x64 ran on linux/x64Overall (-0.12% to +0.00%)
FullOpts (-0.13% to +0.00%)
Details here |
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cc @dotnet/jit-contrib, @AndyAyersMS PTAL. |
Diff results for #97681Assembly diffsAssembly diffs for linux/x64 ran on windows/x64Diffs are based on 2,517,901 contexts (991,070 MinOpts, 1,526,831 FullOpts). MISSED contexts: 8 (0.00%) Overall (-50,401 bytes)
FullOpts (-50,401 bytes)
Assembly diffs for windows/x64 ran on windows/x64Diffs are based on 2,512,204 contexts (997,391 MinOpts, 1,514,813 FullOpts). MISSED contexts: 8 (0.00%) Overall (-52,115 bytes)
FullOpts (-52,115 bytes)
Details here Assembly diffs for windows/x86 ran on windows/x86Diffs are based on 2,293,423 contexts (839,658 MinOpts, 1,453,765 FullOpts). MISSED contexts: base: 38 (0.00%), diff: 73 (0.00%) Overall (-22,900 bytes)
FullOpts (-22,900 bytes)
Details here Throughput diffsThroughput diffs for linux/arm ran on windows/x86Overall (+0.01% to +0.04%)
FullOpts (+0.01% to +0.04%)
Throughput diffs for windows/x86 ran on windows/x86Overall (+0.02% to +0.06%)
FullOpts (+0.03% to +0.06%)
Details here Throughput diffs for linux/arm64 ran on linux/x64Overall (-0.14% to +0.00%)
FullOpts (-0.16% to +0.00%)
Throughput diffs for linux/x64 ran on linux/x64Overall (-0.12% to +0.00%)
FullOpts (-0.13% to +0.00%)
Details here |
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I've put this work on hold in favor of the successor edge items in #93020. I'll come back to this. |
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Follow-up to #97488. In
fgUpdateFlowGraph, we already have a check for convertingBBJ_CONDblocks toBBJ_ALWAYSblocks when the true and false targets are the same. This PR marginally improves the number of cases we can optimize by checking if the true/false target is aBBJ_ALWAYSto the false/true target. This pattern can occur inadvertently if a block's false target is an emptyBBJ_ALWAYSto the "real" false target (in other words, theBBJ_ALWAYSwas inserted to maintain the implicit fallthrough invariant during block reordering), and other flowgraph optimizations (like compacting) cause theBBJ_ALWAYSblock to point to the true target. In such cases, we can convert theBBJ_CONDblock to aBBJ_ALWAYSblock, and potentially delete the emptyBBJ_ALWAYS.