Remove redundant alignment calculation

ParkHanbum · ParkHanbum · commit de865353e301 · 2024-10-17T21:19:18.000+09:00
diff --git a/llvm/lib/Transforms/Scalar/InferAlignment.cpp b/llvm/lib/Transforms/Scalar/InferAlignment.cpp
@@ -63,10 +63,8 @@ bool inferAlignment(Function &F, AssumptionCache &AC, DominatorTree &DT) {
     for (Instruction &I : BB) {
       Changed |= tryToImproveAlign(
           DL, &I, [&](Value *PtrOp, Align OldAlign, Align PrefAlign) {
-            KnownBits Known = computeKnownBits(PtrOp, DL, 0, &AC, &I, &DT);
-            unsigned TrailZ = std::min(Known.countMinTrailingZeros(),
-                                       +Value::MaxAlignmentExponent);
-            return Align(1ull << std::min(Known.getBitWidth() - 1, TrailZ));
+            return getOrEnforceKnownAlignment(PtrOp, MaybeAlign(), DL, &I, &AC,
+                                              &DT);
           });
     }
   }

Original file line number	Diff line number	Diff line change
`@@ -63,10 +63,8 @@ bool inferAlignment(Function &F, AssumptionCache &AC, DominatorTree &DT) {`
`63`	`63`	`for (Instruction &I : BB) {`
`64`	`64`	`Changed \|= tryToImproveAlign(`
`65`	`65`	`DL, &I, [&](Value *PtrOp, Align OldAlign, Align PrefAlign) {`
`66`		`- KnownBits Known = computeKnownBits(PtrOp, DL, 0, &AC, &I, &DT);`
`67`		`- unsigned TrailZ = std::min(Known.countMinTrailingZeros(),`
`68`		`- +Value::MaxAlignmentExponent);`
`69`		`- return Align(1ull << std::min(Known.getBitWidth() - 1, TrailZ));`
	`66`	`+ return getOrEnforceKnownAlignment(PtrOp, MaybeAlign(), DL, &I, &AC,`
	`67`	`+ &DT);`
`70`	`68`	`});`
`71`	`69`	`}`
`72`	`70`	`}`