[X86] Avoid repeated hash lookups (NFC) (#129470)

kazutakahirata · web-flow · commit 1891281a1581 · 2025-03-03T01:04:16.000-08:00
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -30269,11 +30269,12 @@ static SDValue LowerShift(SDValue Op, const X86Subtarget &Subtarget,
       if (A.isUndef() || A->getAsAPIntVal().uge(EltSizeInBits))
         continue;
       unsigned CstAmt = A->getAsAPIntVal().getZExtValue();
-      if (UniqueCstAmt.count(CstAmt)) {
-        UniqueCstAmt[CstAmt].setBit(I);
+      auto [It, Inserted] = UniqueCstAmt.try_emplace(CstAmt);
+      if (!Inserted) {
+        It->second.setBit(I);
         continue;
       }
-      UniqueCstAmt[CstAmt] = APInt::getOneBitSet(NumElts, I);
+      It->second = APInt::getOneBitSet(NumElts, I);
     }
     assert(!UniqueCstAmt.empty() && "Illegal constant shift amounts");
   }

Original file line number	Diff line number	Diff line change
`@@ -30269,11 +30269,12 @@ static SDValue LowerShift(SDValue Op, const X86Subtarget &Subtarget,`
`30269`	`30269`	`if (A.isUndef() \|\| A->getAsAPIntVal().uge(EltSizeInBits))`
`30270`	`30270`	`continue;`
`30271`	`30271`	`unsigned CstAmt = A->getAsAPIntVal().getZExtValue();`
`30272`		`- if (UniqueCstAmt.count(CstAmt)) {`
`30273`		`- UniqueCstAmt[CstAmt].setBit(I);`
	`30272`	`+ auto [It, Inserted] = UniqueCstAmt.try_emplace(CstAmt);`
	`30273`	`+ if (!Inserted) {`
	`30274`	`+ It->second.setBit(I);`
`30274`	`30275`	`continue;`
`30275`	`30276`	`}`
`30276`		`- UniqueCstAmt[CstAmt] = APInt::getOneBitSet(NumElts, I);`
	`30277`	`+ It->second = APInt::getOneBitSet(NumElts, I);`
`30277`	`30278`	`}`
`30278`	`30279`	`assert(!UniqueCstAmt.empty() && "Illegal constant shift amounts");`
`30279`	`30280`	`}`