[PATCH] D137046: Allows scalable vectors in ComputeNumSignBits and isKnownNonNull

[Philip Reames via Phabricator via llvm-commits]

reames created this revision.
reames added reviewers: craig.topper, david-arm, paulwalker-arm, asb, frasercrmck, efriedma, RKSimon.
Herald added subscribers: StephenFan, bollu, hiraditya, mcrosier.
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reames requested review of this revision.
Herald added subscribers: llvm-commits, alextsao1999.
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This is a follow up to D136470 <https://reviews.llvm.org/D136470> which extends the same scheme used there to ComputeNumSignBits and isKnownNonNull.  As a reminder, for scalable vectors we track a single bit which is implicitly broadcast to all lanes.  We do not know how many lanes there are statically, and thus have to be conservative along paths which require exact sizes.

(Note: This patch is pending rebase over a couple new tests to demonstrate the change better - expect that Monday.)


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D137046

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Transforms/InstCombine/logical-select.ll


Index: llvm/test/Transforms/InstCombine/logical-select.ll
===================================================================
--- llvm/test/Transforms/InstCombine/logical-select.ll
+++ llvm/test/Transforms/InstCombine/logical-select.ll
@@ -742,13 +742,11 @@
 
 define <vscale x 2 x i64> @bitcast_vec_cond_scalable(<vscale x 16 x i1> %cond, <vscale x 2 x i64> %c, <vscale x 2 x i64> %d) {
 ; CHECK-LABEL: @bitcast_vec_cond_scalable(
-; CHECK-NEXT:    [[S:%.*]] = sext <vscale x 16 x i1> [[COND:%.*]] to <vscale x 16 x i8>
-; CHECK-NEXT:    [[T9:%.*]] = bitcast <vscale x 16 x i8> [[S]] to <vscale x 2 x i64>
-; CHECK-NEXT:    [[NOTT9:%.*]] = xor <vscale x 2 x i64> [[T9]], shufflevector (<vscale x 2 x i64> insertelement (<vscale x 2 x i64> poison, i64 -1, i32 0), <vscale x 2 x i64> poison, <vscale x 2 x i32> zeroinitializer)
-; CHECK-NEXT:    [[T11:%.*]] = and <vscale x 2 x i64> [[NOTT9]], [[C:%.*]]
-; CHECK-NEXT:    [[T12:%.*]] = and <vscale x 2 x i64> [[T9]], [[D:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = or <vscale x 2 x i64> [[T11]], [[T12]]
-; CHECK-NEXT:    ret <vscale x 2 x i64> [[R]]
+; CHECK-NEXT:    [[TMP1:%.*]] = bitcast <vscale x 2 x i64> [[D:%.*]] to <vscale x 16 x i8>
+; CHECK-NEXT:    [[TMP2:%.*]] = bitcast <vscale x 2 x i64> [[C:%.*]] to <vscale x 16 x i8>
+; CHECK-NEXT:    [[TMP3:%.*]] = select <vscale x 16 x i1> [[COND:%.*]], <vscale x 16 x i8> [[TMP1]], <vscale x 16 x i8> [[TMP2]]
+; CHECK-NEXT:    [[TMP4:%.*]] = bitcast <vscale x 16 x i8> [[TMP3]] to <vscale x 2 x i64>
+; CHECK-NEXT:    ret <vscale x 2 x i64> [[TMP4]]
 ;
   %s = sext <vscale x 16 x i1> %cond to <vscale x 16 x i8>
   %t9 = bitcast <vscale x 16 x i8> %s to <vscale x 2 x i64>
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -375,11 +375,6 @@
 
 static unsigned ComputeNumSignBits(const Value *V, unsigned Depth,
                                    const Query &Q) {
-  // FIXME: We currently have no way to represent the DemandedElts of a scalable
-  // vector
-  if (isa<ScalableVectorType>(V->getType()))
-    return 1;
-
   auto *FVTy = dyn_cast<FixedVectorType>(V->getType());
   APInt DemandedElts =
       FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1);
@@ -2448,10 +2443,6 @@
 /// Supports values with integer or pointer type and vectors of integers.
 bool isKnownNonZero(const Value *V, const APInt &DemandedElts, unsigned Depth,
                     const Query &Q) {
-  // FIXME: We currently have no way to represent the DemandedElts of a scalable
-  // vector
-  if (isa<ScalableVectorType>(V->getType()))
-    return false;
 
 #ifndef NDEBUG
   Type *Ty = V->getType();
@@ -2739,11 +2730,6 @@
 }
 
 bool isKnownNonZero(const Value* V, unsigned Depth, const Query& Q) {
-  // FIXME: We currently have no way to represent the DemandedElts of a scalable
-  // vector
-  if (isa<ScalableVectorType>(V->getType()))
-    return false;
-
   auto *FVTy = dyn_cast<FixedVectorType>(V->getType());
   APInt DemandedElts =
       FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1);
@@ -3095,12 +3081,6 @@
                                        const APInt &DemandedElts,
                                        unsigned Depth, const Query &Q) {
   Type *Ty = V->getType();
-
-  // FIXME: We currently have no way to represent the DemandedElts of a scalable
-  // vector
-  if (isa<ScalableVectorType>(Ty))
-    return 1;
-
 #ifndef NDEBUG
   assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth");
 


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