[PATCH] D85759: [SLPVectorizer] Fix regression from cost model refactoring

[Thomas Lively via Phabricator via llvm-commits]

tlively created this revision.
tlively added reviewers: samparker, dfukalov, aheejin, dschuff.
Herald added subscribers: llvm-commits, sunfish, hiraditya, jgravelle-google, sbc100.
Herald added a project: LLVM.
tlively requested review of this revision.

8cc911fa5b06 <https://reviews.llvm.org/rG8cc911fa5b06f055430d006d0640248fcac2a101> refactored the `getIntrinsicInstrCost` function and was
meant to be a nonfunctional change, but it accidentally changed how
costs were calculated in the SLP vectorizer, which regressed
WebAssembly codegen and resulted in a downstream bug report at
https://github.com/emscripten-core/emscripten/issues/11449. This patch
is meant to restore the original behavior.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D85759

Files:
  llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
  llvm/test/Transforms/SLPVectorizer/WebAssembly/no-vectorize-rotate.ll


Index: llvm/test/Transforms/SLPVectorizer/WebAssembly/no-vectorize-rotate.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/SLPVectorizer/WebAssembly/no-vectorize-rotate.ll
@@ -0,0 +1,41 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -slp-vectorizer -instcombine -S | FileCheck %s
+
+; Regression test for a bug in the SLP vectorizer that was causing
+; these rotates to be incorrectly combined into a vector rotate.
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+define void @foo(<2 x i64> %x, <4 x i32> %y, i64* %out) #0 {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT:    [[A:%.*]] = extractelement <2 x i64> [[X:%.*]], i32 0
+; CHECK-NEXT:    [[B:%.*]] = extractelement <4 x i32> [[Y:%.*]], i32 2
+; CHECK-NEXT:    [[CONV6:%.*]] = zext i32 [[B]] to i64
+; CHECK-NEXT:    [[C:%.*]] = tail call i64 @llvm.fshl.i64(i64 [[A]], i64 [[A]], i64 [[CONV6]])
+; CHECK-NEXT:    store i64 [[C]], i64* [[OUT:%.*]], align 8
+; CHECK-NEXT:    [[D:%.*]] = extractelement <2 x i64> [[X]], i32 1
+; CHECK-NEXT:    [[E:%.*]] = extractelement <4 x i32> [[Y]], i32 3
+; CHECK-NEXT:    [[CONV17:%.*]] = zext i32 [[E]] to i64
+; CHECK-NEXT:    [[F:%.*]] = tail call i64 @llvm.fshl.i64(i64 [[D]], i64 [[D]], i64 [[CONV17]])
+; CHECK-NEXT:    [[ARRAYIDX2:%.*]] = getelementptr inbounds i64, i64* [[OUT]], i32 1
+; CHECK-NEXT:    store i64 [[F]], i64* [[ARRAYIDX2]], align 8
+; CHECK-NEXT:    ret void
+;
+  %a = extractelement <2 x i64> %x, i32 0
+  %b = extractelement <4 x i32> %y, i32 2
+  %conv6 = zext i32 %b to i64
+  %c = tail call i64 @llvm.fshl.i64(i64 %a, i64 %a, i64 %conv6)
+  store i64 %c, i64* %out
+  %d = extractelement <2 x i64> %x, i32 1
+  %e = extractelement <4 x i32> %y, i32 3
+  %conv17 = zext i32 %e to i64
+  %f = tail call i64 @llvm.fshl.i64(i64 %d, i64 %d, i64 %conv17)
+  %arrayidx2 = getelementptr inbounds i64, i64* %out, i32 1
+  store i64 %f, i64* %arrayidx2
+  ret void
+}
+
+declare i64 @llvm.fshl.i64(i64, i64, i64)
+
+attributes #0 = {"target-cpu"="generic" "target-features"="+simd128"}
Index: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -3593,7 +3593,15 @@
       Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
 
       // Calculate the cost of the scalar and vector calls.
-      IntrinsicCostAttributes CostAttrs(ID, *CI, 1, 1);
+      SmallVector<Type *, 4> ScalarTys;
+      for (unsigned op = 0, opc = CI->getNumArgOperands(); op != opc; ++op)
+        ScalarTys.push_back(CI->getArgOperand(op)->getType());
+
+      FastMathFlags FMF;
+      if (auto *FPMO = dyn_cast<FPMathOperator>(CI))
+        FMF = FPMO->getFastMathFlags();
+
+      IntrinsicCostAttributes CostAttrs(ID, ScalarTy, ScalarTys, FMF, 1);
       int ScalarEltCost = TTI->getIntrinsicInstrCost(CostAttrs, CostKind);
       if (NeedToShuffleReuses) {
         ReuseShuffleCost -= (ReuseShuffleNumbers - VL.size()) * ScalarEltCost;


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