[PATCH] D24854: [SROA] Drop lifetime.start/end intrinsics when they block promotion.

[Eli Friedman via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL288074: [SROA] Drop lifetime.start/end intrinsics when they block promotion. (authored by efriedma).

Changed prior to commit:
  https://reviews.llvm.org/D24854?vs=74556&id=79454#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D24854

Files:
  llvm/trunk/lib/Transforms/Scalar/SROA.cpp
  llvm/trunk/test/Transforms/SROA/basictest.ll


Index: llvm/trunk/test/Transforms/SROA/basictest.ll
===================================================================
--- llvm/trunk/test/Transforms/SROA/basictest.ll
+++ llvm/trunk/test/Transforms/SROA/basictest.ll
@@ -1672,9 +1672,8 @@
 
 define void @PR27999() unnamed_addr {
 ; CHECK-LABEL: @PR27999(
-; CHECK: alloca [2 x i64], align 8
-; CHECK: call void @llvm.lifetime.start(i64 16,
-; CHECK: call void @llvm.lifetime.end(i64 8,
+; CHECK: entry-block:
+; CHECK-NEXT: ret void
 entry-block:
   %0 = alloca [2 x i64], align 8
   %1 = bitcast [2 x i64]* %0 to i8*
@@ -1684,3 +1683,15 @@
   call void @llvm.lifetime.end(i64 8, i8* %3)
   ret void
 }
+
+define void @PR29139() {
+; CHECK-LABEL: @PR29139(
+; CHECK: bb1:
+; CHECK-NEXT: ret void
+bb1:
+  %e.7.sroa.6.i = alloca i32, align 1
+  %e.7.sroa.6.0.load81.i = load i32, i32* %e.7.sroa.6.i, align 1
+  %0 = bitcast i32* %e.7.sroa.6.i to i8*
+  call void @llvm.lifetime.end(i64 2, i8* %0)
+  ret void
+}
Index: llvm/trunk/lib/Transforms/Scalar/SROA.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Scalar/SROA.cpp
+++ llvm/trunk/lib/Transforms/Scalar/SROA.cpp
@@ -2876,6 +2876,17 @@
     // Record this instruction for deletion.
     Pass.DeadInsts.insert(&II);
 
+    // Lifetime intrinsics are only promotable if they cover the whole alloca.
+    // Therefore, we drop lifetime intrinsics which don't cover the whole
+    // alloca.
+    // (In theory, intrinsics which partially cover an alloca could be
+    // promoted, but PromoteMemToReg doesn't handle that case.)
+    // FIXME: Check whether the alloca is promotable before dropping the
+    // lifetime intrinsics?
+    if (NewBeginOffset != NewAllocaBeginOffset ||
+        NewEndOffset != NewAllocaEndOffset)
+      return true;
+
     ConstantInt *Size =
         ConstantInt::get(cast<IntegerType>(II.getArgOperand(0)->getType()),
                          NewEndOffset - NewBeginOffset);
@@ -2889,12 +2900,7 @@
     (void)New;
     DEBUG(dbgs() << "          to: " << *New << "\n");
 
-    // Lifetime intrinsics are only promotable if they cover the whole alloca.
-    // (In theory, intrinsics which partially cover an alloca could be
-    // promoted, but PromoteMemToReg doesn't handle that case.)
-    bool IsWholeAlloca = NewBeginOffset == NewAllocaBeginOffset &&
-                         NewEndOffset == NewAllocaEndOffset;
-    return IsWholeAlloca;
+    return true;
   }
 
   bool visitPHINode(PHINode &PN) {


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