[PATCH] D147434: [LV] Improve register pressure estimation if MaxLocalUsers is zero

[Yevgeny Rouban via Phabricator via llvm-commits]

yrouban updated this revision to Diff 510993.
yrouban marked an inline comment as done.
yrouban added a comment.

extracted the test to a separate patch.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D147434/new/

https://reviews.llvm.org/D147434

Files:
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
  llvm/test/Transforms/LoopVectorize/X86/interleave-count.ll


Index: llvm/test/Transforms/LoopVectorize/X86/interleave-count.ll
===================================================================
--- llvm/test/Transforms/LoopVectorize/X86/interleave-count.ll
+++ llvm/test/Transforms/LoopVectorize/X86/interleave-count.ll
@@ -7,11 +7,11 @@
 
 define void @test(ptr %dst, i64 %len) {
 ; CHECK-LABEL: LV: Checking a loop in 'test'
-; CHECK:       LV: IC is 8
+; CHECK:       LV: IC is 16
 ;
 ; CHECK-LABEL: define void @test
 ;
-; Number of @llvm.masked.scatter() calls is 8.
+; Number of @llvm.masked.scatter() calls is 16.
 ; CHECK:         call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
 ; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
 ; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
@@ -20,6 +20,14 @@
 ; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
 ; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
 ; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
+; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
+; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
+; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
+; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
+; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
+; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
+; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
+; CHECK-NEXT:    call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
 ; CHECK-NOT:     call void @llvm.masked.scatter.v4f64.v4p0(<4 x double>
 ;
 entry:
Index: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -5814,15 +5814,17 @@
     if (R.LoopInvariantRegs.find(pair.first) != R.LoopInvariantRegs.end())
       LoopInvariantRegs = R.LoopInvariantRegs[pair.first];
 
-    unsigned TmpIC = llvm::bit_floor((TargetNumRegisters - LoopInvariantRegs) /
-                                     MaxLocalUsers);
-    // Don't count the induction variable as interleaved.
     if (EnableIndVarRegisterHeur) {
-      TmpIC = llvm::bit_floor((TargetNumRegisters - LoopInvariantRegs - 1) /
-                              std::max(1U, (MaxLocalUsers - 1)));
+      // Treat the induction variable as a LoopInvariantReg.
+      assert(MaxLocalUsers);
+      --MaxLocalUsers;
+      ++LoopInvariantRegs;
+    }
+    if (MaxLocalUsers > 0) {
+      unsigned TmpIC = llvm::bit_floor(
+          (TargetNumRegisters - LoopInvariantRegs) / MaxLocalUsers);
+      IC = std::min(IC, TmpIC);
     }
-
-    IC = std::min(IC, TmpIC);
   }
 
   // Clamp the interleave ranges to reasonable counts.


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