Revert "[LAA] Support pointer phis in loop by analyzing each incoming pointer."

This reverts commit 1ed7f8ede564c3b11da4fdca30c36ccbff422576.

This change can cause loop-distribute to crash in some cases. Revert
until I have more time to wrap up a fix.

See  PR50296, PR5028 and D102266.

diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
index 3535058..3248b2a 100644 (file)
--- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
@@ -1938,18 +1938,7 @@ void LoopAccessInfo::analyzeLoop(AAResults *AA, LoopInfo *LI,
       if (blockNeedsPredication(ST->getParent(), TheLoop, DT))
         Loc.AATags.TBAA = nullptr;
 
-      // SCEV does not look through non-header PHIs inside the loop. Such phis
-      // can be analyzed by adding separate accesses for each incoming pointer
-      // value.
-      auto *PN = dyn_cast<PHINode>(Loc.Ptr);
-      if (PN && TheLoop->contains(PN->getParent()) &&
-          PN->getParent() != TheLoop->getHeader()) {
-        for (const Use &Inc : PN->incoming_values()) {
-          MemoryLocation NewLoc = Loc.getWithNewPtr(Inc);
-          Accesses.addStore(NewLoc);
-        }
-      } else
-        Accesses.addStore(Loc);
+      Accesses.addStore(Loc);
     }
   }
 
@@ -1993,17 +1982,7 @@ void LoopAccessInfo::analyzeLoop(AAResults *AA, LoopInfo *LI,
     if (blockNeedsPredication(LD->getParent(), TheLoop, DT))
       Loc.AATags.TBAA = nullptr;
 
-    // SCEV does not look through non-header PHIs inside the loop. Such phis can
-    // be analyzed by adding separate accesses for each incoming pointer value.
-    auto *PN = dyn_cast<PHINode>(Loc.Ptr);
-    if (PN && TheLoop->contains(PN->getParent()) &&
-        PN->getParent() != TheLoop->getHeader()) {
-      for (const Use &Inc : PN->incoming_values()) {
-        MemoryLocation NewLoc = Loc.getWithNewPtr(Inc);
-        Accesses.addLoad(NewLoc, IsReadOnlyPtr);
-      }
-    } else
-      Accesses.addLoad(Loc, IsReadOnlyPtr);
+    Accesses.addLoad(Loc, IsReadOnlyPtr);
   }
 
   // If we write (or read-write) to a single destination and there are no

diff --git a/llvm/test/Analysis/LoopAccessAnalysis/pointer-phis.ll b/llvm/test/Analysis/LoopAccessAnalysis/pointer-phis.ll
index dcdf6dd..c803825 100644 (file)
--- a/llvm/test/Analysis/LoopAccessAnalysis/pointer-phis.ll
+++ b/llvm/test/Analysis/LoopAccessAnalysis/pointer-phis.ll
@@ -6,7 +6,7 @@
 define i32 @load_with_pointer_phi_no_runtime_checks(%s1* %data) {
 ; CHECK-LABEL: load_with_pointer_phi_no_runtime_checks
 ; CHECK-NEXT:  loop.header:
-; CHECK-NEXT:    Memory dependences are safe
+; CHECK-NEXT:    Report: cannot identify array bounds
 ;
 entry:
   br label %loop.header
@@ -41,7 +41,7 @@ exit:                                             ; preds = %loop.latch
 define i32 @store_with_pointer_phi_no_runtime_checks(%s1* %data) {
 ; CHECK-LABEL: 'store_with_pointer_phi_no_runtime_checks'
 ; CHECK-NEXT:  loop.header:
-; CHECK-NEXT:    Memory dependences are safe
+; CHECK-NEXT:    Report: cannot identify array bounds
 ;
 entry:
   br label %loop.header
@@ -76,23 +76,7 @@ exit:                                             ; preds = %loop.latch
 define i32 @store_with_pointer_phi_runtime_checks(double* %A, double* %B, double* %C) {
 ; CHECK-LABEL: 'store_with_pointer_phi_runtime_checks'
 ; CHECK-NEXT:  loop.header:
-; CHECK-NEXT:    Memory dependences are safe with run-time checks
-; CHECK:         Run-time memory checks:
-; CHECK-NEXT:    Check 0:
-; CHECK-NEXT:      Comparing group ([[GROUP_C:.+]]):
-; CHECK-NEXT:        %gep.2 = getelementptr inbounds double, double* %C, i64 %iv
-; CHECK-NEXT:      Against group ([[GROUP_B:.+]]):
-; CHECK-NEXT:        %gep.1 = getelementptr inbounds double, double* %B, i64 %iv
-; CHECK-NEXT:    Check 1:
-; CHECK-NEXT:      Comparing group ([[GROUP_C]]):
-; CHECK-NEXT:        %gep.2 = getelementptr inbounds double, double* %C, i64 %iv
-; CHECK-NEXT:      Against group ([[GROUP_A:.+]]):
-; CHECK-NEXT:        %arrayidx = getelementptr inbounds double, double* %A, i64 %iv
-; CHECK-NEXT:    Check 2:
-; CHECK-NEXT:      Comparing group ([[GROUP_B]]):
-; CHECK-NEXT:        %gep.1 = getelementptr inbounds double, double* %B, i64 %iv
-; CHECK-NEXT:      Against group ([[GROUP_A]]):
-; CHECK-NEXT:        %arrayidx = getelementptr inbounds double, double* %A, i64 %iv
+; CHECK-NEXT:    Report: cannot identify array bounds
 ;
 entry:
   br label %loop.header

diff --git a/llvm/test/Transforms/LoopVectorize/vectorize-pointer-phis.ll b/llvm/test/Transforms/LoopVectorize/vectorize-pointer-phis.ll
index e3168d5..53437e3 100644 (file)
--- a/llvm/test/Transforms/LoopVectorize/vectorize-pointer-phis.ll
+++ b/llvm/test/Transforms/LoopVectorize/vectorize-pointer-phis.ll
@@ -4,8 +4,7 @@
 
 define i32 @load_with_pointer_phi_no_runtime_checks(%s1* %data) {
 ; CHECK-LABEL: @load_with_pointer_phi_no_runtime_checks
-; CHECK-NOT: memcheck
-; CHECK:     vector.body:
+; CHECK-NOT: vector.body
 ;
 entry:
   br label %loop.header
@@ -39,8 +38,7 @@ exit:                                             ; preds = %loop.latch
 
 define i32 @store_with_pointer_phi_no_runtime_checks(%s1* %data) {
 ; CHECK-LABEL: @store_with_pointer_phi_no_runtime_checks
-; CHECK-NOT: memcheck
-; CHECK:     vector.body
+; CHECK-NOT: vector.body
 ;
 entry:
   br label %loop.header
@@ -74,8 +72,7 @@ exit:                                             ; preds = %loop.latch
 
 define i32 @store_with_pointer_phi_runtime_checks(double* %A, double* %B, double* %C) {
 ; CHECK-LABEL: @store_with_pointer_phi_runtime_checks
-; CHECK:     memcheck
-; CHECK:     vector.body
+; CHECK-NOT: vector.body
 ;
 entry:
   br label %loop.header