[ValueTracking] Add logic for `isKnownNonZero(sshl.sat/ushl.sat X, Y)`

`(sshl/ushl X, Y) != 0` -> `X != 0`

Alive2 Links
    https://alive2.llvm.org/ce/z/4WLM2p
    https://alive2.llvm.org/ce/z/BHFng4

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D149411

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index da369c9..0439f4e 100644 (file)
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -2920,6 +2920,8 @@ bool isKnownNonZero(const Value *V, const APInt &DemandedElts, unsigned Depth,
   case Instruction::Call:
     if (auto *II = dyn_cast<IntrinsicInst>(I)) {
       switch (II->getIntrinsicID()) {
+      case Intrinsic::sshl_sat:
+      case Intrinsic::ushl_sat:
       case Intrinsic::abs:
       case Intrinsic::bitreverse:
       case Intrinsic::bswap:

diff --git a/llvm/test/Analysis/ValueTracking/known-non-zero.ll b/llvm/test/Analysis/ValueTracking/known-non-zero.ll
index 52f809c..61cbe13 100644 (file)
--- a/llvm/test/Analysis/ValueTracking/known-non-zero.ll
+++ b/llvm/test/Analysis/ValueTracking/known-non-zero.ll
@@ -803,10 +803,7 @@ define i1 @sshl_nonzero(i8 %xx, i8 %y, i8 %ind) {
 ; CHECK-LABEL: @sshl_nonzero(
 ; CHECK-NEXT:    [[X_NZ:%.*]] = icmp ne i8 [[XX:%.*]], 0
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[X_NZ]])
-; CHECK-NEXT:    [[X:%.*]] = call i8 @llvm.sshl.sat.i8(i8 [[XX]], i8 [[Y:%.*]])
-; CHECK-NEXT:    [[Z:%.*]] = or i8 [[X]], [[IND:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[Z]], 0
-; CHECK-NEXT:    ret i1 [[R]]
+; CHECK-NEXT:    ret i1 false
 ;
   %x_nz = icmp ne i8 %xx, 0
   call void @llvm.assume(i1 %x_nz)
@@ -833,10 +830,7 @@ define i1 @ushl_nonzero(i8 %xx, i8 %y, i8 %ind) {
 ; CHECK-LABEL: @ushl_nonzero(
 ; CHECK-NEXT:    [[X_NZ:%.*]] = icmp ne i8 [[XX:%.*]], 0
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[X_NZ]])
-; CHECK-NEXT:    [[X:%.*]] = call i8 @llvm.ushl.sat.i8(i8 [[XX]], i8 [[Y:%.*]])
-; CHECK-NEXT:    [[Z:%.*]] = or i8 [[X]], [[IND:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[Z]], 0
-; CHECK-NEXT:    ret i1 [[R]]
+; CHECK-NEXT:    ret i1 false
 ;
   %x_nz = icmp ne i8 %xx, 0
   call void @llvm.assume(i1 %x_nz)