[MIPatternMatch] Add m_OneNonDBGUse

[paquette]

Summary

Add a matcher that checks if the given subpattern has only one non-debug use.

Also improve existing m_OneUse testcase.

[aemerson]

LGTM.

llvm/include/llvm/CodeGen/GlobalISel/MIPatternMatch.h

template <typename SubPatternT> struct OneUse_match {
   }
 };
 
 template <typename SubPat>
 inline OneUse_match<SubPat> m_OneUse(const SubPat &SP) {
   return SP;
 }
 
+template <typename SubPatternT> struct OneNonDBGUse_match {
+  SubPatternT SubPat;
+  OneNonDBGUse_match(const SubPatternT &SP) : SubPat(SP) {}
+
+  bool match(const MachineRegisterInfo &MRI, Register Reg) {
+    return MRI.hasOneNonDBGUse(Reg) && SubPat.match(MRI, Reg);
+  }
+};
+
+template <typename SubPat>
+inline OneNonDBGUse_match<SubPat> m_OneNonDBGUse(const SubPat &SP) {
+  return SP;
+}
+
 struct ConstantMatch {
   int64_t &CR;
   ConstantMatch(int64_t &C) : CR(C) {}
   bool match(const MachineRegisterInfo &MRI, Register Reg) {
     if (auto MaybeCst = getConstantVRegSExtVal(Reg, MRI)) {
       CR = *MaybeCst;
       return true;
     }

llvm/unittests/CodeGen/GlobalISel/PatternMatchTest.cpp

 
 TEST_F(AArch64GISelMITest, MatchMiscellaneous) {
   setUp();
   if (!TM)
     return;
 
   LLT s64 = LLT::scalar(64);
   auto MIBAdd = B.buildAdd(s64, Copies[0], Copies[1]);
-  // Make multiple uses of this add.
+  Register Reg = MIBAdd.getReg(0);
+
+  // Only one use of Reg.
   B.buildCast(LLT::pointer(0, 32), MIBAdd);
+  EXPECT_TRUE(mi_match(Reg, *MRI, m_OneUse(m_GAdd(m_Reg(), m_Reg()))));
+  EXPECT_TRUE(mi_match(Reg, *MRI, m_OneNonDBGUse(m_GAdd(m_Reg(), m_Reg()))));
+
+  // Add multiple debug uses of Reg.
+  B.buildInstr(TargetOpcode::DBG_VALUE, {}, {Reg})->getOperand(0).setIsDebug();
+  B.buildInstr(TargetOpcode::DBG_VALUE, {}, {Reg})->getOperand(0).setIsDebug();
+
+  EXPECT_FALSE(mi_match(Reg, *MRI, m_OneUse(m_GAdd(m_Reg(), m_Reg()))));
+  EXPECT_TRUE(mi_match(Reg, *MRI, m_OneNonDBGUse(m_GAdd(m_Reg(), m_Reg()))));
+
+  // Multiple non-debug uses of Reg.
   B.buildCast(LLT::pointer(1, 32), MIBAdd);
-  bool match = mi_match(MIBAdd.getReg(0), *MRI, m_GAdd(m_Reg(), m_Reg()));
-  EXPECT_TRUE(match);
-  match = mi_match(MIBAdd.getReg(0), *MRI, m_OneUse(m_GAdd(m_Reg(), m_Reg())));
-  EXPECT_FALSE(match);
+  EXPECT_FALSE(mi_match(Reg, *MRI, m_OneUse(m_GAdd(m_Reg(), m_Reg()))));
+  EXPECT_FALSE(mi_match(Reg, *MRI, m_OneNonDBGUse(m_GAdd(m_Reg(), m_Reg()))));
 }
 
 TEST_F(AArch64GISelMITest, MatchSpecificConstant) {
   setUp();
   if (!TM)
     return;
 
   // Basic case: Can we match a G_CONSTANT with a specific value?