[SCCP] Add nneg flag to uitofp if its operand is non-negative

Similiar to the `InstCombine` changes, just furthering the support of
the `uitofp nneg` support.

Author: goldsteinn

llvm/lib/Transforms/Utils/SCCPSolver.cpp

@@ -143,7 +143,7 @@ static bool refineInstruction(SCCPSolver &Solver,
         Changed = true;
       }
     }
-  } else if (isa<ZExtInst>(Inst) && !Inst.hasNonNeg()) {
+  } else if (isa<PossiblyNonNegInst>(Inst) && !Inst.hasNonNeg()) {
     auto Range = GetRange(Inst.getOperand(0));
     if (Range.isAllNonNegative()) {
       Inst.setNonNeg();
@@ -191,14 +191,16 @@ static bool replaceSignedInst(SCCPSolver &Solver,
 
   Instruction *NewInst = nullptr;
   switch (Inst.getOpcode()) {
-  // Note: We do not fold sitofp -> uitofp here because that could be more
-  // expensive in codegen and may not be reversible in the backend.
+  case Instruction::SIToFP:
   case Instruction::SExt: {
-    // If the source value is not negative, this is a zext.
+    // If the source value is not negative, this is a zext/uitofp.
     Value *Op0 = Inst.getOperand(0);
     if (InsertedValues.count(Op0) || !isNonNegative(Op0))
       return false;
-    NewInst = new ZExtInst(Op0, Inst.getType(), "", Inst.getIterator());
+    NewInst = CastInst::Create(Inst.getOpcode() == Instruction::SExt
+                                   ? Instruction::ZExt
+                                   : Instruction::UIToFP,
+                               Op0, Inst.getType(), "", Inst.getIterator());
     NewInst->setNonNeg();
     break;
   }

llvm/test/Transforms/SCCP/ip-ranges-casts.ll

@@ -167,7 +167,7 @@ define i1 @caller.sext() {
 define internal i1 @f.fptosi(i32 %x) {
 ; CHECK-LABEL: define internal i1 @f.fptosi(
 ; CHECK-SAME: i32 [[X:%.*]]) {
-; CHECK-NEXT:    [[TO_DOUBLE:%.*]] = sitofp i32 [[X]] to double
+; CHECK-NEXT:    [[TO_DOUBLE:%.*]] = uitofp nneg i32 [[X]] to double
 ; CHECK-NEXT:    [[ADD:%.*]] = fadd double 0.000000e+00, [[TO_DOUBLE]]
 ; CHECK-NEXT:    [[TO_I32:%.*]] = fptosi double [[ADD]] to i32
 ; CHECK-NEXT:    [[C_1:%.*]] = icmp sgt i32 [[TO_I32]], 300
@@ -209,7 +209,7 @@ define i1 @caller.fptosi() {
 define internal i1 @f.fpext(i16 %x) {
 ; CHECK-LABEL: define internal i1 @f.fpext(
 ; CHECK-SAME: i16 [[X:%.*]]) {
-; CHECK-NEXT:    [[TO_FLOAT:%.*]] = sitofp i16 [[X]] to float
+; CHECK-NEXT:    [[TO_FLOAT:%.*]] = uitofp nneg i16 [[X]] to float
 ; CHECK-NEXT:    [[TO_DOUBLE:%.*]] = fpext float [[TO_FLOAT]] to double
 ; CHECK-NEXT:    [[TO_I64:%.*]] = fptoui float [[TO_FLOAT]] to i64
 ; CHECK-NEXT:    [[C_1:%.*]] = icmp sgt i64 [[TO_I64]], 300
@@ -293,7 +293,7 @@ define i1 @int_range_to_double_cast(i32 %a) {
 ; CHECK-LABEL: define i1 @int_range_to_double_cast(
 ; CHECK-SAME: i32 [[A:%.*]]) {
 ; CHECK-NEXT:    [[R:%.*]] = and i32 [[A]], 255
-; CHECK-NEXT:    [[T4:%.*]] = sitofp i32 [[R]] to double
+; CHECK-NEXT:    [[T4:%.*]] = uitofp nneg i32 [[R]] to double
 ; CHECK-NEXT:    [[T10:%.*]] = fadd double 0.000000e+00, [[T4]]
 ; CHECK-NEXT:    [[T11:%.*]] = fcmp olt double [[T4]], [[T10]]
 ; CHECK-NEXT:    ret i1 [[T11]]

llvm/test/Transforms/SCCP/sitofp.ll

@@ -4,7 +4,7 @@
 define float @sitofp_and(i8 %x) {
 ; CHECK-LABEL: @sitofp_and(
 ; CHECK-NEXT:    [[PX:%.*]] = and i8 [[X:%.*]], 127
-; CHECK-NEXT:    [[R:%.*]] = sitofp i8 [[PX]] to float
+; CHECK-NEXT:    [[R:%.*]] = uitofp nneg i8 [[PX]] to float
 ; CHECK-NEXT:    ret float [[R]]
 ;
   %px = and i8 %x, 127
@@ -23,7 +23,7 @@ define half @sitofp_const(i8 %x) {
 define double @sitofp_zext(i7 %x) {
 ; CHECK-LABEL: @sitofp_zext(
 ; CHECK-NEXT:    [[PX:%.*]] = zext i7 [[X:%.*]] to i8
-; CHECK-NEXT:    [[R:%.*]] = sitofp i8 [[PX]] to double
+; CHECK-NEXT:    [[R:%.*]] = uitofp nneg i8 [[PX]] to double
 ; CHECK-NEXT:    ret double [[R]]
 ;
   %px = zext i7 %x to i8
@@ -52,7 +52,7 @@ define float @dominating_condition(i32 %x) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp sge i32 [[X:%.*]], 0
 ; CHECK-NEXT:    br i1 [[CMP]], label [[T:%.*]], label [[F:%.*]]
 ; CHECK:       t:
-; CHECK-NEXT:    [[A:%.*]] = sitofp i32 [[X]] to float
+; CHECK-NEXT:    [[A:%.*]] = uitofp nneg i32 [[X]] to float
 ; CHECK-NEXT:    br label [[EXIT:%.*]]
 ; CHECK:       f:
 ; CHECK-NEXT:    br label [[EXIT]]
@@ -86,7 +86,7 @@ define float @dominating_condition_alt(i32 %x) {
 ; CHECK:       t:
 ; CHECK-NEXT:    br label [[EXIT:%.*]]
 ; CHECK:       f:
-; CHECK-NEXT:    [[A:%.*]] = sitofp i32 [[X]] to float
+; CHECK-NEXT:    [[A:%.*]] = uitofp nneg i32 [[X]] to float
 ; CHECK-NEXT:    br label [[EXIT]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    [[COND:%.*]] = phi float [ -4.200000e+01, [[T]] ], [ [[A]], [[F]] ]