[LoopInterchange] Remove 'S' Scalar Dependencies

llvm/lib/Transforms/Scalar/LoopInterchange.cpp

@@ -136,23 +136,17 @@ static bool populateDependencyMatrix(CharMatrix &DepMatrix, unsigned Level,
         unsigned Levels = D->getLevels();
         char Direction;
         for (unsigned II = 1; II <= Levels; ++II) {
-          if (D->isScalar(II)) {
-            Direction = 'S';
-            Dep.push_back(Direction);
-          } else {
-            unsigned Dir = D->getDirection(II);
-            if (Dir == Dependence::DVEntry::LT ||
-                Dir == Dependence::DVEntry::LE)
-              Direction = '<';
-            else if (Dir == Dependence::DVEntry::GT ||
-                     Dir == Dependence::DVEntry::GE)
-              Direction = '>';
-            else if (Dir == Dependence::DVEntry::EQ)
-              Direction = '=';
-            else
-              Direction = '*';
-            Dep.push_back(Direction);
-          }
+          unsigned Dir = D->getDirection(II);
+          if (Dir == Dependence::DVEntry::LT || Dir == Dependence::DVEntry::LE)
+            Direction = '<';
+          else if (Dir == Dependence::DVEntry::GT ||
+                   Dir == Dependence::DVEntry::GE)
+            Direction = '>';
+          else if (Dir == Dependence::DVEntry::EQ)
+            Direction = '=';
+          else
+            Direction = '*';
+          Dep.push_back(Direction);
         }
         while (Dep.size() != Level) {
           Dep.push_back('I');

llvm/test/Transforms/LoopInterchange/gh54176-scalar-deps.ll

@@ -1,3 +1,11 @@
+; Remove 'S' Scalar Dependencies #119345
+; Scalar dependencies are not handled correctly, so they were removed to avoid
+; miscompiles. The loop nest in this test case used to be interchanged, but it's
+; no longer triggering. XFAIL'ing this test to indicate that this test should
+; interchanged if scalar deps are handled correctly.
+;
+; XFAIL: *
+
 ; RUN: opt < %s -passes=loop-interchange -pass-remarks-output=%t -disable-output
 ; RUN: FileCheck -input-file %t %s
 

llvm/test/Transforms/LoopInterchange/inner-only-reductions.ll

@@ -2,8 +2,11 @@
 ; RUN:     -verify-dom-info -verify-loop-info -verify-loop-lcssa 2>&1 | FileCheck -check-prefix=IR %s
 ; RUN: FileCheck --input-file=%t %s
 
-; Inner loop only reductions are not supported currently. See discussion at
-; D53027 for more information on the required checks.
+; Both tests should be rejected as interchange candidates. For now, they are
+; rejected for dependence analysis reasons, but that's because support for 'S'
+; scalar dependencies was removed. When that is properly, the inner loop only
+; reductions should still not be supported currently, see discussion at D53027
+; for more information on the required checks.
 
 @A = common global [500 x [500 x i32]] zeroinitializer
 @X = common global i32 0
@@ -18,7 +21,7 @@
 
 ; CHECK: --- !Missed
 ; CHECK-NEXT: Pass:            loop-interchange
-; CHECK-NEXT: Name:            UnsupportedPHI
+; CHECK-NEXT: Name:            Dependence
 ; CHECK-NEXT: Function:        reduction_01
 
 ; IR-LABEL: @reduction_01(
@@ -71,7 +74,7 @@ for.end8:                                         ; preds = %for.cond1.for.inc6_
 
 ; CHECK: --- !Missed
 ; CHECK-NEXT: Pass:            loop-interchange
-; CHECK-NEXT: Name:            UnsupportedPHIOuter
+; CHECK-NEXT: Name:            Dependence
 ; CHECK-NEXT: Function:        reduction_03
 
 ; IR-LABEL: @reduction_03(

llvm/test/Transforms/LoopInterchange/innermost-latch-uses-values-in-middle-header.ll

@@ -1,3 +1,11 @@
+; Remove 'S' Scalar Dependencies #119345
+; Scalar dependencies are not handled correctly, so they were removed to avoid
+; miscompiles. The loop nest in this test case used to be interchanged, but it's
+; no longer triggering. XFAIL'ing this test to indicate that this test should
+; interchanged if scalar deps are handled correctly.
+;
+; XFAIL: *
+
 ; RUN: opt < %s -passes=loop-interchange -verify-dom-info -verify-loop-info -pass-remarks-output=%t -disable-output
 ; RUN: FileCheck -input-file %t %s
 

llvm/test/Transforms/LoopInterchange/interchange-flow-dep-outer.ll

@@ -1,3 +1,11 @@
+; Remove 'S' Scalar Dependencies #119345
+; Scalar dependencies are not handled correctly, so they were removed to avoid
+; miscompiles. The loop nest in this test case used to be interchanged, but it's
+; no longer triggering. XFAIL'ing this test to indicate that this test should
+; interchanged if scalar deps are handled correctly.
+;
+; XFAIL: *
+
 ; RUN: opt < %s -passes=loop-interchange -cache-line-size=64 -verify-dom-info -verify-loop-info -pass-remarks-output=%t -disable-output
 ; RUN: FileCheck -input-file %t %s
 

llvm/test/Transforms/LoopInterchange/lcssa.ll

@@ -1,3 +1,11 @@
+; Remove 'S' Scalar Dependencies #119345
+; Scalar dependencies are not handled correctly, so they were removed to avoid
+; miscompiles. The loop nest in this test case used to be interchanged, but it's
+; no longer triggering. XFAIL'ing this test to indicate that this test should
+; interchanged if scalar deps are handled correctly.
+;
+; XFAIL: *
+
 ; RUN: opt < %s -passes=loop-interchange -cache-line-size=64 -pass-remarks-missed='loop-interchange' -verify-loop-lcssa -pass-remarks-output=%t -S
 ; RUN: FileCheck --input-file %t --check-prefix REMARK %s
 
@@ -177,7 +185,7 @@ for.end16:                                        ; preds = %for.exit
 }
 
 ; PHI node in inner latch with multiple predecessors.
-; REMARK: Interchanged
+; REMARK:      Interchanged
 ; REMARK-NEXT: lcssa_05
 
 define void @lcssa_05(ptr %ptr, i1 %arg) {
@@ -222,7 +230,7 @@ for.end16:                                        ; preds = %for.exit
   ret void
 }
 
-; REMARK: UnsupportedExitPHI
+; REMARK:      UnsupportedExitPHI
 ; REMARK-NEXT: lcssa_06
 
 define void @lcssa_06(ptr %ptr, ptr %ptr1, i1 %arg) {

llvm/test/Transforms/LoopInterchange/outer-header-jump-to-inner-latch.ll

@@ -1,3 +1,11 @@
+; Remove 'S' Scalar Dependencies #119345
+; Scalar dependencies are not handled correctly, so they were removed to avoid
+; miscompiles. The loop nest in this test case used to be interchanged, but it's
+; no longer triggering. XFAIL'ing this test to indicate that this test should
+; interchanged if scalar deps are handled correctly.
+;
+; XFAIL: *
+
 ; RUN: opt -passes=loop-interchange -cache-line-size=64 -verify-dom-info -verify-loop-info -verify-loop-lcssa %s -pass-remarks-output=%t -disable-output
 ; RUN: FileCheck -input-file %t %s
 

llvm/test/Transforms/LoopInterchange/pr43176-move-to-new-latch.ll

@@ -14,10 +14,10 @@
 
 ; CHECK: --- !Missed
 ; CHECK-NEXT: Pass:            loop-interchange
-; CHECK-NEXT: Name:            InterchangeNotProfitable
+; CHECK-NEXT: Name:            Dependence
 ; CHECK-NEXT: Function:        test1
 ; CHECK-NEXT: Args:
-; CHECK-NEXT:  - String:          Interchanging loops is not considered to improve cache locality nor vectorization.
+; CHECK-NEXT:  - String:       Cannot interchange loops due to dependences.
 
 define void @test1() {
 entry:
@@ -54,10 +54,10 @@ for.cond.for.end5_crit_edge:                      ; preds = %for.inc3
 
 ; CHECK: --- !Missed
 ; CHECK-NEXT: Pass:            loop-interchange
-; CHECK-NEXT: Name:            InterchangeNotProfitable
+; CHECK-NEXT: Name:            Dependence
 ; CHECK-NEXT: Function:        test2
 ; CHECK-NEXT: Args:
-; CHECK-NEXT:  - String:          Interchanging loops is not considered to improve cache locality nor vectorization.
+; CHECK-NEXT:  - String:       Cannot interchange loops due to dependences.
 
 define void @test2() {
 entry:

llvm/test/Transforms/LoopInterchange/pr43797-lcssa-for-multiple-outer-loop-blocks.ll

@@ -1,3 +1,11 @@
+; Remove 'S' Scalar Dependencies #119345
+; Scalar dependencies are not handled correctly, so they were removed to avoid
+; miscompiles. The loop nest in this test case used to be interchanged, but it's
+; no longer triggering. XFAIL'ing this test to indicate that this test should
+; interchanged if scalar deps are handled correctly.
+;
+; XFAIL: *
+
 ; RUN: opt -passes=loop-interchange -cache-line-size=64 -verify-loop-lcssa %s -pass-remarks-output=%t -disable-output
 ; RUN: FileCheck -input-file %t %s
 

llvm/test/Transforms/LoopInterchange/profitability.ll

@@ -1,3 +1,11 @@
+; Remove 'S' Scalar Dependencies #119345
+; Scalar dependencies are not handled correctly, so they were removed to avoid
+; miscompiles. The loop nest in this test case used to be interchanged, but it's
+; no longer triggering. XFAIL'ing this test to indicate that this test should
+; interchanged if scalar deps are handled correctly.
+;
+; XFAIL: *
+
 ; RUN: opt < %s -passes=loop-interchange -cache-line-size=64 -pass-remarks-output=%t -verify-dom-info -verify-loop-info \
 ; RUN:     -pass-remarks=loop-interchange -pass-remarks-missed=loop-interchange
 ; RUN: FileCheck -input-file %t %s

llvm/test/Transforms/LoopInterchange/reductions-across-inner-and-outer-loop.ll

@@ -153,7 +153,7 @@ for1.loopexit:                                 ; preds = %for1.inc
 ; Check that we do not interchange if reduction is stored in an invariant address inside inner loop
 ; REMARKS: --- !Missed
 ; REMARKS-NEXT: Pass:            loop-interchange
-; REMARKS-NEXT: Name:            UnsupportedPHIOuter
+; REMARKS-NEXT: Name:            Dependence
 ; REMARKS-NEXT: Function:        test4
 
 define i64 @test4(ptr %Arr, ptr %dst) {

llvm/test/Transforms/LoopInterchange/unique-dep-matrix.ll

@@ -3,8 +3,8 @@
 
 ; CHECK:       Dependency matrix before interchange:
 ; CHECK-NEXT:  I I
-; CHECK-NEXT:  = S
-; CHECK-NEXT:  < S
+; CHECK-NEXT:  = *
+; CHECK-NEXT:  < *
 ; CHECK-NEXT:  Processing InnerLoopId
 
 ; This example is taken from github issue #54176

llvm/test/Transforms/LoopInterchange/vector-gep-operand.ll

@@ -1,3 +1,11 @@
+; Remove 'S' Scalar Dependencies #119345
+; Scalar dependencies are not handled correctly, so they were removed to avoid
+; miscompiles. The loop nest in this test case used to be interchanged, but it's
+; no longer triggering. XFAIL'ing this test to indicate that this test should
+; interchanged if scalar deps are handled correctly.
+;
+; XFAIL: *
+
 ; RUN: opt -passes=loop-interchange -cache-line-size=64 -loop-interchange-threshold=-10 %s -pass-remarks-output=%t -disable-output
 ; RUN: FileCheck -input-file %t %s