[llvm] [IPO] Avoid repeated hash lookups (NFC) (PR #125639)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/125639

The two "if" conditions are mutually exclusive, so we can put them in
any order.  Reversing the order allows us to remove
Blocks.contains(IncomingBlock) in one of the "if" conditions.


>From daddf96517b9e2005944199143eaf4341b2d2438 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Mon, 3 Feb 2025 16:33:06 -0800
Subject: [PATCH] [IPO] Avoid repeated hash lookups (NFC)

The two "if" conditions are mutually exclusive, so we can put them in
any order.  Reversing the order allows us to remove
Blocks.contains(IncomingBlock) in one of the "if" conditions.
---
 llvm/lib/Transforms/IPO/IROutliner.cpp | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/llvm/lib/Transforms/IPO/IROutliner.cpp b/llvm/lib/Transforms/IPO/IROutliner.cpp
index 41bc67f2b6891b..34ddeeb37400cf 100644
--- a/llvm/lib/Transforms/IPO/IROutliner.cpp
+++ b/llvm/lib/Transforms/IPO/IROutliner.cpp
@@ -1184,22 +1184,22 @@ static std::optional<unsigned> getGVNForPHINode(OutlinableRegion &Region,
   for (unsigned Idx = 0, EIdx = PN->getNumIncomingValues(); Idx < EIdx; Idx++) {
     Incoming = PN->getIncomingValue(Idx);
     IncomingBlock = PN->getIncomingBlock(Idx);
+    // If the incoming block isn't in the region, we don't have to worry about
+    // this incoming value.
+    if (!Blocks.contains(IncomingBlock))
+      continue;
+
     // If we cannot find a GVN, and the incoming block is included in the region
     // this means that the input to the PHINode is not included in the region we
     // are trying to analyze, meaning, that if it was outlined, we would be
     // adding an extra input.  We ignore this case for now, and so ignore the
     // region.
     std::optional<unsigned> OGVN = Cand.getGVN(Incoming);
-    if (!OGVN && Blocks.contains(IncomingBlock)) {
+    if (!OGVN) {
       Region.IgnoreRegion = true;
       return std::nullopt;
     }
 
-    // If the incoming block isn't in the region, we don't have to worry about
-    // this incoming value.
-    if (!Blocks.contains(IncomingBlock))
-      continue;
-
     // Collect the canonical numbers of the values in the PHINode.
     unsigned GVN = *OGVN;
     OGVN = Cand.getCanonicalNum(GVN);