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[LoopVectorize] Remove redundant code in emitSCEVChecks #111132
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There was some code in emitSCEVChecks to update the dominator tree if LoopBypassBlocks is empty, however there are no tests that fail when replacing this code with an assert. I built both SPEC2017 and the LLVM test suite and also didn't see any build failures. I've removed the code for now and added an assert to guard this in case anything changes, since it seems pointless to have code that's impossible to defend.
@llvm/pr-subscribers-llvm-transforms Author: David Sherwood (david-arm) ChangesThere was some code in emitSCEVChecks to update the dominator Full diff: https://github.com/llvm/llvm-project/pull/111132.diff 1 Files Affected:
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index de3b981a4fe390..7c7d6693a1dccd 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -2486,18 +2486,8 @@ BasicBlock *InnerLoopVectorizer::emitSCEVChecks(BasicBlock *Bypass) {
(OptForSizeBasedOnProfile &&
Cost->Hints->getForce() != LoopVectorizeHints::FK_Enabled)) &&
"Cannot SCEV check stride or overflow when optimizing for size");
-
-
- // Update dominator only if this is first RT check.
- if (LoopBypassBlocks.empty()) {
- DT->changeImmediateDominator(Bypass, SCEVCheckBlock);
- if (!Cost->requiresScalarEpilogue(VF.isVector()))
- // If there is an epilogue which must run, there's no edge from the
- // middle block to exit blocks and thus no need to update the immediate
- // dominator of the exit blocks.
- DT->changeImmediateDominator(LoopExitBlock, SCEVCheckBlock);
- }
-
+ assert(!LoopBypassBlocks.empty() &&
+ "Should already be a bypass block due to iteration count check");
LoopBypassBlocks.push_back(SCEVCheckBlock);
AddedSafetyChecks = true;
return SCEVCheckBlock;
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LGTM, thanks! This should never be the first RT check in the current version.
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/151/builds/2658 Here is the relevant piece of the build log for the reference
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* commit 'FETCH_HEAD': [X86] getIntImmCostInst - pull out repeated Imm.getBitWidth() calls. NFC. [X86] Add test coverage for llvm#111323 [Driver] Use empty multilib file in another test (llvm#111352) [clang][OpenMP][test] Use x86_64-linux-gnu triple for test referencing avx512f feature (llvm#111337) [doc] Fix Kaleidoscope tutorial chapter 3 code snippet and full listing discrepancies (llvm#111289) [Flang][OpenMP] Improve entry block argument creation and binding (llvm#110267) [x86] combineMul - handle 0/-1 KnownBits cases before MUL_IMM logic (REAPPLIED) [llvm-dis] Fix non-deterministic disassembly across multiple inputs (llvm#110988) [lldb][test] TestDataFormatterLibcxxOptionalSimulator.py: change order of ifdefs [lldb][test] Add libcxx-simulators test for std::optional (llvm#111133) [x86] combineMul - use computeKnownBits directly to find MUL_IMM constant splat. (REAPPLIED) Reland "[lldb][test] TestDataFormatterLibcxxStringSimulator.py: add new padding layout" (llvm#111123) Revert "[x86] combineMul - use computeKnownBits directly to find MUL_IMM constant splat." update_test_checks: fix a simple regression (llvm#111347) [LegalizeVectorTypes] Always widen fabs (llvm#111298) [lsan] Make ReportUnsuspendedThreads return bool also for Fuchsia [mlir][vector] Add more tests for ConvertVectorToLLVM (6/n) (llvm#111121) [bazel] port 9144fed [SystemZ] Remove inlining threshold multiplier. (llvm#106058) [LegalizeVectorTypes] When widening don't check for libcalls if promoted (llvm#111297) [clang][Driver] Improve multilib custom error reporting (llvm#110804) [clang][Driver] Rename "FatalError" key to "Error" in multilib.yaml (llvm#110804) [LLVM][Maintainers] Update release managers (llvm#111164) [Clang][Driver] Add option to provide path for multilib's YAML config file (llvm#109640) [LoopVectorize] Remove redundant code in emitSCEVChecks (llvm#111132) [AMDGPU] Only emit SCOPE_SYS global_wb (llvm#110636) [ELF] Change Ctx::target to unique_ptr (llvm#111260) [ELF] Pass Ctx & to some free functions [RISCV] Only disassemble fcvtmod.w.d if the rounding mode is rtz. (llvm#111308) [Clang] Remove the special-casing for RequiresExprBodyDecl in BuildResolvedCallExpr() after fd87d76 (llvm#111277) [ELF] Pass Ctx & to InputFile [clang-format] Add AlignFunctionDeclarations to AlignConsecutiveDeclarations (llvm#108241) [AMDGPU] Support preloading hidden kernel arguments (llvm#98861) [ELF] Move static nextGroupId isInGroup to LinkerDriver [clangd] Add ArgumentLists config option under Completion (llvm#111322) [ELF] Pass Ctx & to SyntheticSections [ELF] Pass Ctx & to Symbols [ELF] Pass Ctx & to Symbols [ELF] getRelocTargetVA: pass Ctx and Relocation. NFC [clang-tidy] Avoid capturing a local variable in a static lambda in UseRangesCheck (llvm#111282) [VPlan] Use pointer to member 0 as VPInterleaveRecipe's pointer arg. (llvm#106431) [clangd] Simplify ternary expressions with std::optional::value_or (NFC) (llvm#111309) [libc++][format][2/3] Optimizes c-string arguments. (llvm#101805) [RISCV] Combine RVBUnary and RVKUnary into classes that are more similar to ALU(W)_r(r/i). NFC (llvm#111279) [ELF] Pass Ctx & to InputFiles [libc] GPU RPC interface: add return value to `rpc_host_call` (llvm#111288) Signed-off-by: kyvangka1610 <[email protected]>
There was some code in emitSCEVChecks to update the dominator
tree if LoopBypassBlocks is empty, however there are no tests
that fail when replacing this code with an assert. I built
both SPEC2017 and the LLVM test suite and also didn't see any
build failures. I've removed the code for now and added an
assert to guard this in case anything changes, since it seems
pointless to have code that's impossible to defend.