[SDAG] Lower range attribute to AssertZext

Author: andjo403

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

@@ -4487,6 +4487,18 @@ static const MDNode *getRangeMetadata(const Instruction &I) {
   return I.getMetadata(LLVMContext::MD_range);
 }
 
+static std::optional<ConstantRange> getRange(const Instruction &I) {
+  if (const auto *CB = dyn_cast<CallBase>(&I)) {
+    // see comment in getRangeMetadata about this check
+    if (CB->hasRetAttr(Attribute::NoUndef))
+      return CB->getRange();
+  }
+  if (const MDNode *Range = getRangeMetadata(I)) {
+    return getConstantRangeFromMetadata(*Range);
+  }
+  return std::nullopt;
+}
+
 void SelectionDAGBuilder::visitLoad(const LoadInst &I) {
   if (I.isAtomic())
     return visitAtomicLoad(I);
@@ -10229,19 +10241,16 @@ void SelectionDAGBuilder::visitVACopy(const CallInst &I) {
 SDValue SelectionDAGBuilder::lowerRangeToAssertZExt(SelectionDAG &DAG,
                                                     const Instruction &I,
                                                     SDValue Op) {
-  const MDNode *Range = getRangeMetadata(I);
-  if (!Range)
-    return Op;
+  std::optional<ConstantRange> CR = getRange(I);
 
-  ConstantRange CR = getConstantRangeFromMetadata(*Range);
-  if (CR.isFullSet() || CR.isEmptySet() || CR.isUpperWrapped())
+  if (!CR || CR->isFullSet() || CR->isEmptySet() || CR->isUpperWrapped())
     return Op;
 
-  APInt Lo = CR.getUnsignedMin();
+  APInt Lo = CR->getUnsignedMin();
   if (!Lo.isMinValue())
     return Op;
 
-  APInt Hi = CR.getUnsignedMax();
+  APInt Hi = CR->getUnsignedMax();
   unsigned Bits = std::max(Hi.getActiveBits(),
                            static_cast<unsigned>(IntegerType::MIN_INT_BITS));
 

llvm/test/CodeGen/AArch64/lower-range-metadata-func-call.ll

@@ -34,9 +34,10 @@ entry:
   ret i32 %and
 }
 
+; and can be eliminated
 ; CHECK-LABEL: {{^}}test_call_known_max_range_attr:
 ; CHECK: bl foo
-; CHECK: and w{{[0-9]+}}, w0, #0x3ff
+; CHECK-NOT: and
 ; CHECK: ret
 define i32 @test_call_known_max_range_attr() #0 {
 entry:
@@ -56,7 +57,6 @@ entry:
   ret i32 %and
 }
 
-
 declare i32 @foo()
 
 attributes #0 = { norecurse nounwind }

llvm/test/CodeGen/X86/legalize-vec-assertzext.ll

@@ -39,6 +39,9 @@ define i64 @widen_assertzext_range_attr(ptr %x) nounwind {
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    pushq %rax
 ; CHECK-NEXT:    callq test2@PLT
+; CHECK-NEXT:    movb $127, %al
+; CHECK-NEXT:    kmovw %eax, %k1
+; CHECK-NEXT:    vpexpandq %zmm0, %zmm0 {%k1} {z}
 ; CHECK-NEXT:    vextracti32x4 $3, %zmm0, %xmm0
 ; CHECK-NEXT:    vmovq %xmm0, %rax
 ; CHECK-NEXT:    popq %rcx