[PATCH] D124967: [SROA] Avoid postponing rewriting load/store by ignoring lifetime intrinsics in partition's promotability checking

[Dmitry Vassiliev via Phabricator via llvm-commits]

slydiman updated this revision to Diff 429845.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D124967/new/

https://reviews.llvm.org/D124967

Files:
  llvm/lib/Transforms/Scalar/SROA.cpp
  llvm/test/Transforms/SROA/lifetime-intrinsic.ll


Index: llvm/test/Transforms/SROA/lifetime-intrinsic.ll
===================================================================
--- llvm/test/Transforms/SROA/lifetime-intrinsic.ll
+++ llvm/test/Transforms/SROA/lifetime-intrinsic.ll
@@ -11,11 +11,9 @@
 
 define i16 @with_lifetime(i32 %a, i32 %b) #0 {
 ; CHECK-LABEL: @with_lifetime(
-; CHECK-NEXT:    [[ARR_SROA_0_SROA_0_0_EXTRACT_TRUNC:%.*]] = trunc i32 [[A:%.*]] to i16
-; CHECK-NEXT:    [[ARR_SROA_0_SROA_4_0_EXTRACT_SHIFT:%.*]] = lshr i32 [[A]], 16
-; CHECK-NEXT:    [[ARR_SROA_0_SROA_4_0_EXTRACT_TRUNC:%.*]] = trunc i32 [[ARR_SROA_0_SROA_4_0_EXTRACT_SHIFT]] to i16
+; CHECK-NEXT:    [[ARR_SROA_0_0_EXTRACT_TRUNC:%.*]] = trunc i32 [[A:%.*]] to i16
 ; CHECK-NEXT:    [[ARR_SROA_4_4_EXTRACT_TRUNC:%.*]] = trunc i32 [[B:%.*]] to i16
-; CHECK-NEXT:    [[RET:%.*]] = add i16 [[ARR_SROA_0_SROA_0_0_EXTRACT_TRUNC]], [[ARR_SROA_4_4_EXTRACT_TRUNC]]
+; CHECK-NEXT:    [[RET:%.*]] = add i16 [[ARR_SROA_0_0_EXTRACT_TRUNC]], [[ARR_SROA_4_4_EXTRACT_TRUNC]]
 ; CHECK-NEXT:    ret i16 [[RET]]
 ;
   %arr = alloca %i32x2, align 4
Index: llvm/lib/Transforms/Scalar/SROA.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/SROA.cpp
+++ llvm/lib/Transforms/Scalar/SROA.cpp
@@ -1983,13 +1983,22 @@
   uint64_t RelBegin = S.beginOffset() - AllocBeginOffset;
   uint64_t RelEnd = S.endOffset() - AllocBeginOffset;
 
+  Use *U = S.getUse();
+
+  // Lifetime intrinsics operate over the whole alloca whose sizes are usually
+  // larger than other load/store slices (RelEnd > Size). But lifetime are
+  // always promotable and should not impact other slices' promotability of the
+  // partition.
+  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U->getUser())) {
+    if (II->isLifetimeStartOrEnd() || II->isDroppable())
+      return true;
+  }
+
   // We can't reasonably handle cases where the load or store extends past
   // the end of the alloca's type and into its padding.
   if (RelEnd > Size)
     return false;
 
-  Use *U = S.getUse();
-
   if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) {
     if (LI->isVolatile())
       return false;
@@ -2044,9 +2053,6 @@
       return false;
     if (!S.isSplittable())
       return false; // Skip any unsplittable intrinsics.
-  } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U->getUser())) {
-    if (!II->isLifetimeStartOrEnd() && !II->isDroppable())
-      return false;
   } else {
     return false;
   }


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