[llvm] [GlobalISel] Add constant matcher for APInt (PR #151357)

[Matt Arsenault via llvm-commits]

================
@@ -192,63 +192,92 @@ m_GFCstOrSplat(std::optional<FPValueAndVReg> &FPValReg) {
 
 /// Matcher for a specific constant value.
 struct SpecificConstantMatch {
-  int64_t RequestedVal;
-  SpecificConstantMatch(int64_t RequestedVal) : RequestedVal(RequestedVal) {}
+  APInt RequestedVal;
+  SpecificConstantMatch(APInt RequestedVal) : RequestedVal(RequestedVal) {}
   bool match(const MachineRegisterInfo &MRI, Register Reg) {
-    int64_t MatchedVal;
-    return mi_match(Reg, MRI, m_ICst(MatchedVal)) && MatchedVal == RequestedVal;
+    APInt MatchedVal;
+    if (mi_match(Reg, MRI, m_ICst(MatchedVal))) {
+      if (MatchedVal.getBitWidth() > RequestedVal.getBitWidth())
+        RequestedVal = RequestedVal.sext(MatchedVal.getBitWidth());
+      else
+        MatchedVal = MatchedVal.sext(RequestedVal.getBitWidth());
+
+      return APInt::isSameValue(MatchedVal, RequestedVal);
+    }
+    return false;
   }
 };
 
 /// Matches a constant equal to \p RequestedValue.
+inline SpecificConstantMatch m_SpecificICst(APInt RequestedValue) {
+  return SpecificConstantMatch(std::move(RequestedValue));
+}
+
 inline SpecificConstantMatch m_SpecificICst(int64_t RequestedValue) {
-  return SpecificConstantMatch(RequestedValue);
+  return SpecificConstantMatch(APInt(64, RequestedValue, /* isSigned */ true));
 }
 
 /// Matcher for a specific constant splat.
 struct SpecificConstantSplatMatch {
-  int64_t RequestedVal;
-  SpecificConstantSplatMatch(int64_t RequestedVal)
-      : RequestedVal(RequestedVal) {}
+  APInt RequestedVal;
+  SpecificConstantSplatMatch(APInt RequestedVal) : RequestedVal(RequestedVal) {}
   bool match(const MachineRegisterInfo &MRI, Register Reg) {
     return isBuildVectorConstantSplat(Reg, MRI, RequestedVal,
                                       /* AllowUndef */ false);
   }
 };
 
 /// Matches a constant splat of \p RequestedValue.
+inline SpecificConstantSplatMatch m_SpecificICstSplat(APInt RequestedValue) {
+  return SpecificConstantSplatMatch(std::move(RequestedValue));
+}
+
 inline SpecificConstantSplatMatch m_SpecificICstSplat(int64_t RequestedValue) {
-  return SpecificConstantSplatMatch(RequestedValue);
+  return SpecificConstantSplatMatch(
+      APInt(64, RequestedValue, /* isSigned */ true));
 }
 
 /// Matcher for a specific constant or constant splat.
 struct SpecificConstantOrSplatMatch {
-  int64_t RequestedVal;
-  SpecificConstantOrSplatMatch(int64_t RequestedVal)
+  APInt RequestedVal;
+  SpecificConstantOrSplatMatch(APInt RequestedVal)
       : RequestedVal(RequestedVal) {}
   bool match(const MachineRegisterInfo &MRI, Register Reg) {
-    int64_t MatchedVal;
-    if (mi_match(Reg, MRI, m_ICst(MatchedVal)) && MatchedVal == RequestedVal)
-      return true;
+    APInt MatchedVal;
+    if (mi_match(Reg, MRI, m_ICst(MatchedVal))) {
+      if (MatchedVal.getBitWidth() > RequestedVal.getBitWidth())
+        RequestedVal = RequestedVal.sext(MatchedVal.getBitWidth());
+      else
+        MatchedVal = MatchedVal.sext(RequestedVal.getBitWidth());
+
+      if (APInt::isSameValue(MatchedVal, RequestedVal))
+        return true;
+    }
     return isBuildVectorConstantSplat(Reg, MRI, RequestedVal,
                                       /* AllowUndef */ false);
   }
 };
 
 /// Matches a \p RequestedValue constant or a constant splat of \p
 /// RequestedValue.
+inline SpecificConstantOrSplatMatch
+m_SpecificICstOrSplat(APInt RequestedValue) {
+  return SpecificConstantOrSplatMatch(std::move(RequestedValue));
+}
+
 inline SpecificConstantOrSplatMatch
 m_SpecificICstOrSplat(int64_t RequestedValue) {
-  return SpecificConstantOrSplatMatch(RequestedValue);
+  return SpecificConstantOrSplatMatch(
+      APInt(64, RequestedValue, /* isSigned */ true));
 }
 
-///{
 /// Convenience matchers for specific integer values.
-inline SpecificConstantMatch m_ZeroInt() { return SpecificConstantMatch(0); }
+inline SpecificConstantMatch m_ZeroInt() {
+  return SpecificConstantMatch(APInt(64, 0));
----------------
arsenm wrote:

Better to use the isNullValue in APInt (really for all of these, should follow along with the IR pattern matcher structure) 

https://github.com/llvm/llvm-project/pull/151357