[PatternMatch] Remove 64-bit or less restriction from m_SpecificInt

[craig.topper]

Summary

Not sure why this restriction existed, but it seems like we should support any size Constant here.

The particular pattern in the tests is not the only use of this matcher in the tree. There's one in CodeGenPrepare and one in InstSimplify as well. I can try to add test cases for those if we want.

[davide]

I don't have the tree handy here, but do you happen to know when this was introduced?

[craig.topper]

It looks like when m_SpecificInt was added in https://reviews.llvm.org/rL216586 in Aug 2014 it came with this restriction. I wonder if it was borrowed from the m_ConstantInt that writes to a uint64_t that's located right next to it in the file.

[hfinkel]

In D34666#791657, @craig.topper wrote:

It looks like when m_SpecificInt was added in https://reviews.llvm.org/rL216586 in Aug 2014 it came with this restriction. I wonder if it was borrowed from the m_ConstantInt that writes to a uint64_t that's located right next to it in the file.

Seems likely.

LGTM.

llvm/trunk/include/llvm/IR/PatternMatch.h

struct specific_intval {
   specific_intval(uint64_t V) : Val(V) {}
 
   template <typename ITy> bool match(ITy *V) {
     const auto *CI = dyn_cast<ConstantInt>(V);
     if (!CI && V->getType()->isVectorTy())
       if (const auto *C = dyn_cast<Constant>(V))
         CI = dyn_cast_or_null<ConstantInt>(C->getSplatValue());
 
-    if (CI && CI->getBitWidth() <= 64)
-      return CI->getZExtValue() == Val;
-
-    return false;
+    return CI && CI->getValue() == Val;
   }
 };
 
 /// \brief Match a specific integer value or vector with all elements equal to
 /// the value.
 inline specific_intval m_SpecificInt(uint64_t V) { return specific_intval(V); }
 
 /// \brief Match a ConstantInt and bind to its value.  This does not match

llvm/trunk/test/Transforms/InstCombine/select-cmp-cttz-ctlz.ll

entry:
   %conv = trunc i32 %0 to i16
   %tobool = icmp ne i32 %x, 0
   %cond = select i1 %tobool, i16 %conv, i16 32
   ret i16 %cond
 }
 
 define i128 @test7(i128 %x) {
 ; CHECK-LABEL: @test7(
-; CHECK-NEXT:    [[TMP0:%.*]] = tail call i128 @llvm.ctlz.i128(i128 [[X:%.*]], i1 true), !range !3
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp ne i128 [[X]], 0
-; CHECK-NEXT:    [[COND:%.*]] = select i1 [[TOBOOL]], i128 [[TMP0]], i128 128
-; CHECK-NEXT:    ret i128 [[COND]]
+; CHECK-NEXT:    [[TMP1:%.*]] = tail call i128 @llvm.ctlz.i128(i128 [[X:%.*]], i1 false), !range !3
+; CHECK-NEXT:    ret i128 [[TMP1]]
 ;
   %1 = tail call i128 @llvm.ctlz.i128(i128 %x, i1 true)
   %tobool = icmp ne i128 %x, 0
   %cond = select i1 %tobool, i128 %1, i128 128
   ret i128 %cond
 }
 
 define i128 @test8(i128 %x) {
 ; CHECK-LABEL: @test8(
-; CHECK-NEXT:    [[TMP0:%.*]] = tail call i128 @llvm.cttz.i128(i128 [[X:%.*]], i1 true), !range !3
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp ne i128 [[X]], 0
-; CHECK-NEXT:    [[COND:%.*]] = select i1 [[TOBOOL]], i128 [[TMP0]], i128 128
-; CHECK-NEXT:    ret i128 [[COND]]
+; CHECK-NEXT:    [[TMP1:%.*]] = tail call i128 @llvm.cttz.i128(i128 [[X:%.*]], i1 false), !range !3
+; CHECK-NEXT:    ret i128 [[TMP1]]
 ;
   %1 = tail call i128 @llvm.cttz.i128(i128 %x, i1 true)
   %tobool = icmp ne i128 %x, 0
   %cond = select i1 %tobool, i128 %1, i128 128
   ret i128 %cond
 }
 
 declare i16 @llvm.ctlz.i16(i16, i1)
 declare i32 @llvm.ctlz.i32(i32, i1)
 declare i64 @llvm.ctlz.i64(i64, i1)
 declare i128 @llvm.ctlz.i128(i128, i1)
 declare i16 @llvm.cttz.i16(i16, i1)
 declare i32 @llvm.cttz.i32(i32, i1)
 declare i64 @llvm.cttz.i64(i64, i1)
 declare i128 @llvm.cttz.i128(i128, i1)