[SCCP] Handle some negative cases.

Author: dtcxzyw

llvm/lib/Transforms/Utils/SCCPSolver.cpp

@@ -307,7 +307,7 @@ static Value *simplifyInstruction(SCCPSolver &Solver,
       // Match icmp eq/ne X & NegPow2, C
       if (ICmp->isEquality()) {
         const APInt *Mask;
-        if (match(LHS, m_And(m_Value(X), m_NegatedPower2(Mask))) &&
+        if (match(LHS, m_OneUse(m_And(m_Value(X), m_NegatedPower2(Mask)))) &&
             RHSC->countr_zero() >= Mask->countr_zero()) {
           ConstantRange CR(*RHSC, *RHSC - *Mask);
           return Pred == ICmpInst::ICMP_EQ ? CR : CR.inverse();
@@ -318,6 +318,8 @@ static Value *simplifyInstruction(SCCPSolver &Solver,
 
     if (auto CR = MatchTwoInstructionExactRangeCheck()) {
       ConstantRange LRange = GetRange(X);
+      if (LRange.isFullSet())
+        return nullptr;
       if (auto NewCR = CR->exactUnionWith(LRange.inverse())) {
         ICmpInst::Predicate Pred;
         APInt RHS;

llvm/test/Transforms/SCCP/conditions-ranges-with-undef.ll

@@ -40,7 +40,7 @@ define void @val_undef_range() {
 ; CHECK-LABEL: @val_undef_range(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[A:%.*]] = add nuw nsw i32 undef, 0
-; CHECK-NEXT:    [[BC_1:%.*]] = icmp ult i32 undef, 127
+; CHECK-NEXT:    [[BC_1:%.*]] = icmp ult i32 [[A]], 127
 ; CHECK-NEXT:    br i1 [[BC_1]], label [[TRUE:%.*]], label [[FALSE:%.*]]
 ; CHECK:       true:
 ; CHECK-NEXT:    call void @use(i1 false)

llvm/test/Transforms/SCCP/relax-range-checks.ll

@@ -48,3 +48,31 @@ define i1 @relax_range_check_not_profitable(i8 range(i8 0, 6) %x)  {
   %ret = icmp ult i8 %add, 2
   ret i1 %ret
 }
+
+define i1 @relax_range_check_unknown_range(i64 %x)  {
+; CHECK-LABEL: define i1 @relax_range_check_unknown_range(
+; CHECK-SAME: i64 [[X:%.*]]) {
+; CHECK-NEXT:    [[AND:%.*]] = and i64 [[X]], -67108864
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i64 [[AND]], 0
+; CHECK-NEXT:    ret i1 [[TMP1]]
+;
+  %and = and i64 %x, -67108864
+  %test = icmp eq i64 %and, 0
+  ret i1 %test
+}
+
+define i1 @relax_range_check_highbits_check_multiuse(i8 range(i8 2, 0) %x)  {
+; CHECK-LABEL: define i1 @relax_range_check_highbits_check_multiuse(
+; CHECK-SAME: i8 range(i8 2, 0) [[X:%.*]]) {
+; CHECK-NEXT:    [[AND:%.*]] = and i8 [[X]], -2
+; CHECK-NEXT:    call void @use(i8 [[AND]])
+; CHECK-NEXT:    [[RET:%.*]] = icmp eq i8 [[AND]], 2
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %and = and i8 %x, -2
+  call void @use(i8 %and)
+  %ret = icmp eq i8 %and, 2
+  ret i1 %ret
+}
+
+declare void @use(i8)