[Intrinsics] Add support for range attributes

Add support for specifying range attributes in Intrinsics.td. Use
this to specify the ucmp/scmp range [-1,2).

This case is trickier than existing intrinsic attributes, because
we need to create the attribute with the correct bitwidth. As such,
the attribute construction now needs to be aware of the function
type.

We also need to be careful to no longer assign attributes on
intrinsics with invalid signatures, as we'd make invalid assumptions
about the number of arguments etc otherwise.

Author: nikic

llvm/include/llvm/IR/Intrinsics.h

@@ -86,7 +86,7 @@ namespace Intrinsic {
   ID lookupIntrinsicID(StringRef Name);
 
   /// Return the attributes for an intrinsic.
-  AttributeList getAttributes(LLVMContext &C, ID id);
+  AttributeList getAttributes(LLVMContext &C, ID id, FunctionType *FT);
 
   /// Return the function attributes for an intrinsic.
   AttributeSet getFnAttributes(LLVMContext &C, ID id);

llvm/include/llvm/IR/Intrinsics.td

@@ -134,6 +134,14 @@ class ReadNone<ArgIndex idx> : IntrinsicProperty {
   int ArgNo = idx.Value;
 }
 
+// The return value or argument is in the range [lower, upper),
+// where lower and upper are interpreted as signed integers.
+class Range<AttrIndex idx, int lower, int upper> : IntrinsicProperty {
+  int ArgNo = idx.Value;
+  int Lower = lower;
+  int Upper = upper;
+}
+
 def IntrNoReturn : IntrinsicProperty;
 
 // Applied by default.
@@ -1620,10 +1628,10 @@ def int_umin : DefaultAttrsIntrinsic<
     [IntrNoMem, IntrSpeculatable, IntrWillReturn]>;
 def int_scmp : DefaultAttrsIntrinsic<
     [llvm_anyint_ty], [llvm_anyint_ty, LLVMMatchType<1>],
-    [IntrNoMem, IntrSpeculatable, IntrWillReturn]>;
+    [IntrNoMem, IntrSpeculatable, IntrWillReturn, Range<RetIndex, -1, 2>]>;
 def int_ucmp : DefaultAttrsIntrinsic<
     [llvm_anyint_ty], [llvm_anyint_ty, LLVMMatchType<1>],
-    [IntrNoMem, IntrSpeculatable, IntrWillReturn]>;
+    [IntrNoMem, IntrSpeculatable, IntrWillReturn, Range<RetIndex, -1, 2>]>;
 
 //===------------------------- Memory Use Markers -------------------------===//
 //

llvm/lib/IR/AutoUpgrade.cpp

@@ -1519,8 +1519,14 @@ bool llvm::UpgradeIntrinsicFunction(Function *F, Function *&NewFn,
   // Upgrade intrinsic attributes.  This does not change the function.
   if (NewFn)
     F = NewFn;
-  if (Intrinsic::ID id = F->getIntrinsicID())
-    F->setAttributes(Intrinsic::getAttributes(F->getContext(), id));
+  if (Intrinsic::ID id = F->getIntrinsicID()) {
+    // Only do this if the intrinsic signature is valid.
+    SmallVector<Type *> OverloadTys;
+    if (Intrinsic::getIntrinsicSignature(id, F->getFunctionType(),
+                                         OverloadTys))
+      F->setAttributes(
+          Intrinsic::getAttributes(F->getContext(), id, F->getFunctionType()));
+  }
   return Upgraded;
 }
 

llvm/lib/IR/Function.cpp

@@ -514,8 +514,15 @@ Function::Function(FunctionType *Ty, LinkageTypes Linkage, unsigned AddrSpace,
   // Ensure intrinsics have the right parameter attributes.
   // Note, the IntID field will have been set in Value::setName if this function
   // name is a valid intrinsic ID.
-  if (IntID)
-    setAttributes(Intrinsic::getAttributes(getContext(), IntID));
+  if (IntID) {
+    // Don't set the attributes if the intrinsic signature is invalid. This
+    // case will either be auto-upgraded or fail verification.
+    SmallVector<Type *> OverloadTys;
+    if (!Intrinsic::getIntrinsicSignature(IntID, Ty, OverloadTys))
+      return;
+
+    setAttributes(Intrinsic::getAttributes(getContext(), IntID, Ty));
+  }
 }
 
 Function::~Function() {

llvm/lib/IR/Intrinsics.cpp

@@ -13,6 +13,7 @@
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringTable.h"
+#include "llvm/IR/ConstantRange.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/IntrinsicsAArch64.h"
 #include "llvm/IR/IntrinsicsAMDGPU.h"

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

@@ -16506,7 +16506,8 @@ Align SITargetLowering::computeKnownAlignForTargetInstr(
     // site specifies a lower alignment?
     Intrinsic::ID IID = GI->getIntrinsicID();
     LLVMContext &Ctx = VT.getMachineFunction().getFunction().getContext();
-    AttributeList Attrs = Intrinsic::getAttributes(Ctx, IID);
+    AttributeList Attrs =
+        Intrinsic::getAttributes(Ctx, IID, Intrinsic::getType(Ctx, IID));
     if (MaybeAlign RetAlign = Attrs.getRetAlignment())
       return *RetAlign;
   }

llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp

@@ -2903,7 +2903,7 @@ static void stripNonValidAttributesFromPrototype(Function &F) {
   // assumes that the attributes defined in Intrinsic.td are conservatively
   // correct for both physical and abstract model.
   if (Intrinsic::ID id = F.getIntrinsicID()) {
-    F.setAttributes(Intrinsic::getAttributes(Ctx, id));
+    F.setAttributes(Intrinsic::getAttributes(Ctx, id, F.getFunctionType()));
     return;
   }
 

llvm/test/Assembler/aarch64-intrinsics-attributes.ll

@@ -10,8 +10,8 @@ declare i64 @llvm.aarch64.ldxr.p0(ptr)
 ; CHECK: declare i32 @llvm.aarch64.stxp(i64, i64, ptr) [[NOFREE_NOUNWIND_WILLRETURN]]
 declare i32 @llvm.aarch64.stxp(i64, i64, ptr)
 
-; CHECK: declare i32 @llvm.aarch64.dsb(i32) [[NOFREE_NOUNWIND_WILLRETURN]]
-declare i32 @llvm.aarch64.dsb(i32)
+; CHECK: declare void @llvm.aarch64.dsb(i32) [[NOFREE_NOUNWIND_WILLRETURN]]
+declare void @llvm.aarch64.dsb(i32)
 
 ; CHECK: declare i64 @llvm.aarch64.neon.sqdmulls.scalar(i32, i32) [[NO_CALLBACK_NOFREE_NOSYNC_NOUNWIND_READNONE_WILLRETURN:#[0-9]+]]
 declare i64 @llvm.aarch64.neon.sqdmulls.scalar(i32, i32)

llvm/test/Assembler/autoupgrade-invalid-mem-intrinsics.ll

@@ -1,15 +1,13 @@
-; RUN: not llvm-as < %s -o /dev/null 2>&1 | FileCheck %s
+; RUN: llvm-as < %s | llvm-dis | FileCheck %s
 
 ; Check that remangling code doesn't fail on an intrinsic with wrong signature
+; TODO: This should probably produce an error.
 
-; CHECK: Attribute after last parameter!
-; CHECK-NEXT: ptr @llvm.memset.i64
+; CHECK: declare void @llvm.memset.i64
 declare void @llvm.memset.i64(ptr nocapture, i8, i64) nounwind
 
-; CHECK: Attribute after last parameter!
-; CHECK-NEXT: ptr @llvm.memcpy.i64
+; CHECK: declare void @llvm.memcpy.i64
 declare void @llvm.memcpy.i64(ptr nocapture, i8, i64) nounwind
 
-; CHECK: Attribute after last parameter!
-; CHECK-NEXT: ptr @llvm.memmove.i64
+; CHECK: declare void @llvm.memmove.i64
 declare void @llvm.memmove.i64(ptr nocapture, i8, i64) nounwind

llvm/test/TableGen/intrinsic-attrs.td

@@ -6,8 +6,10 @@ def int_random_gen   : Intrinsic<[llvm_i32_ty], [], [IntrNoMem, IntrHasSideEffec
 
 def int_deref_ptr_ret : Intrinsic<[llvm_ptr_ty], [], [Dereferenceable<RetIndex, 16>]>;
 
-// CHECK: static AttributeSet getIntrinsicArgAttributeSet(LLVMContext &C, unsigned ID) {
-// CHECK-NEXT:   switch (ID) {
+// CHECK: static AttributeSet getIntrinsicArgAttributeSet(LLVMContext &C, unsigned ID,
+// CHECK-NEXT: Type *ArgType) {
+// CHECK-NEXT: unsigned BitWidth = ArgType->getScalarSizeInBits();
+// CHECK-NEXT: switch (ID) {
 // CHECK-NEXT: default: llvm_unreachable("Invalid attribute set number");
 // CHECK-NEXT: case 0:
 // CHECK-NEXT:     return AttributeSet::get(C, {
@@ -26,13 +28,14 @@ def int_deref_ptr_ret : Intrinsic<[llvm_ptr_ty], [], [Dereferenceable<RetIndex,
 // CHECK: 0 << 8 | 0, // llvm.deref.ptr.ret
 // CHECK: 1 << 8 | 1, // llvm.random.gen
 
-// CHECK: getAttributes(LLVMContext &C, ID id)
+// CHECK: getAttributes(LLVMContext &C, ID id,
+// CHECK-NEXT: FunctionType *FT) {
 // CHECK: case 1:
 // CHECK-NEXT: return AttributeList::get(C, {
 // CHECK-NEXT:   {AttributeList::FunctionIndex, getIntrinsicFnAttributeSet(C, FnAttrID)}
 // CHECK-NEXT: });
 // CHECK-NEXT: case 0:
 // CHECK-NEXT: return AttributeList::get(C, {
-// CHECK-NEXT:   {0, getIntrinsicArgAttributeSet(C, 0)},
+// CHECK-NEXT:   {0, getIntrinsicArgAttributeSet(C, 0, FT->getContainedType(0))},
 // CHECK-NEXT:   {AttributeList::FunctionIndex, getIntrinsicFnAttributeSet(C, FnAttrID)}
 // CHECK-NEXT: });