[llvm] [SandboxVectorizer] New class to actually collect and manage seeds (PR #112979)

[via llvm-commits]

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@@ -268,3 +268,171 @@ define void @foo(ptr %ptrA, float %val, ptr %ptrB) {
   }
   EXPECT_EQ(Cnt, 0u);
 }
+
+TEST_F(SeedBundleTest, ConsecutiveStores) {
+  // Where "Consecutive" means the stores address consecutive locations in
+  // memory, but not in program order. Check to see that the collector puts them
+  // in the proper order for vectorization.
+  parseIR(C, R"IR(
+define void @foo(ptr noalias %ptr, float %val) {
+bb:
+  %ptr0 = getelementptr float, ptr %ptr, i32 0
+  %ptr1 = getelementptr float, ptr %ptr, i32 1
+  %ptr2 = getelementptr float, ptr %ptr, i32 2
+  %ptr3 = getelementptr float, ptr %ptr, i32 3
+  store float %val, ptr %ptr0
+  store float %val, ptr %ptr2
+  store float %val, ptr %ptr1
+  store float %val, ptr %ptr3
+  ret void
+}
+)IR");
+  Function &LLVMF = *M->getFunction("foo");
+  DominatorTree DT(LLVMF);
+  TargetLibraryInfoImpl TLII;
+  TargetLibraryInfo TLI(TLII);
+  DataLayout DL(M->getDataLayout());
+  LoopInfo LI(DT);
+  AssumptionCache AC(LLVMF);
+  ScalarEvolution SE(LLVMF, TLI, AC, DT, LI);
+
+  sandboxir::Context Ctx(C);
+  auto &F = *Ctx.createFunction(&LLVMF);
+  auto BB = F.begin();
+  sandboxir::SeedCollector SC(&*BB, SE);
+
+  // Find the stores
+  auto It = std::next(BB->begin(), 4);
+  // StX with X as the order by offset in memory
+  auto *St0 = &*It++;
+  auto *St2 = &*It++;
+  auto *St1 = &*It++;
+  auto *St3 = &*It++;
+
+  auto StoreSeedsRange = SC.getStoreSeeds();
+  auto &SB = *StoreSeedsRange.begin();
+  // Expect just one vector of store seeds
+  EXPECT_TRUE(std::next(StoreSeedsRange.begin()) == StoreSeedsRange.end());
+  EXPECT_THAT(SB, testing::ElementsAre(St0, St1, St2, St3));
+}
+
+TEST_F(SeedBundleTest, StoresWithGaps) {
+  parseIR(C, R"IR(
+define void @foo(ptr noalias %ptr, float %val) {
+bb:
+  %ptr0 = getelementptr float, ptr %ptr, i32 0
+  %ptr1 = getelementptr float, ptr %ptr, i32 3
+  %ptr2 = getelementptr float, ptr %ptr, i32 5
+  %ptr3 = getelementptr float, ptr %ptr, i32 7
+  store float %val, ptr %ptr0
+  store float %val, ptr %ptr2
+  store float %val, ptr %ptr1
+  store float %val, ptr %ptr3
+  ret void
+}
+)IR");
+  Function &LLVMF = *M->getFunction("foo");
+  DominatorTree DT(LLVMF);
+  TargetLibraryInfoImpl TLII;
+  TargetLibraryInfo TLI(TLII);
+  DataLayout DL(M->getDataLayout());
+  LoopInfo LI(DT);
+  AssumptionCache AC(LLVMF);
+  ScalarEvolution SE(LLVMF, TLI, AC, DT, LI);
+
+  sandboxir::Context Ctx(C);
+  auto &F = *Ctx.createFunction(&LLVMF);
+  auto BB = F.begin();
+  sandboxir::SeedCollector SC(&*BB, SE);
+
+  // Find the stores
+  auto It = std::next(BB->begin(), 4);
+  // StX with X as the order by offset in memory
+  auto *St0 = &*It++;
+  auto *St2 = &*It++;
+  auto *St1 = &*It++;
+  auto *St3 = &*It++;
+
+  auto StoreSeedsRange = SC.getStoreSeeds();
+  auto &SB = *StoreSeedsRange.begin();
+  // Expect just one vector of store seeds
----------------
Sterling-Augustine wrote:

This actually brings up another problem, in that a slice could contain two writes to the exact same memory location, which would confuse things like lane-counting and power-of-two calculations.  I suppose one of the stores must be dead in that case, but getSlice doesn't know anything about that. 

Can we assume the scheduler and legality checking obviate that problem? Or should this be a TODO?

https://github.com/llvm/llvm-project/pull/112979