From 8a9c6a346c53f310c310526e0a5ba2b89dd569a0 Mon Sep 17 00:00:00 2001
From: Ruoyu Qiu <cabbaken@outlook.com>
Date: Wed, 11 Mar 2026 15:43:43 +0800
Subject: [PATCH] [DA] refactor bounds inference in exactSIVtest and
 exactRDIVtest  (NFC) (#185719)

Replaces the `SmallVector`-based approach for computing the min/max of
affine domain bounds with `GetMaxOrMin` lambda returning `std::optional`
for better readability.
Previously, the code allocated a `SmallVector` to collect valid bounds
and relied on `smax(front(), back())` to handle the single-element case,
which may cause misunderstanding.

---------

Signed-off-by: Ruoyu Qiu <cabbaken@outlook.com>
---
 llvm/lib/Analysis/DependenceAnalysis.cpp | 50 +++++++++++++-----------
 1 file changed, 27 insertions(+), 23 deletions(-)

diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index ab8a43df2f25..202e8c725863 100644
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -1703,26 +1703,28 @@ bool DependenceInfo::exactSIVtest(const SCEV *SrcCoeff, const SCEV *DstCoeff,
   auto [TL0, TU0] = inferDomainOfAffine(TB, TX, UM);
   auto [TL1, TU1] = inferDomainOfAffine(TA, TY, UM);
 
-  auto CreateVec = [](const OverflowSafeSignedAPInt &V0,
-                      const OverflowSafeSignedAPInt &V1) {
-    SmallVector<APInt, 2> Vec;
+  auto GetMaxOrMin = [](const OverflowSafeSignedAPInt &V0,
+                        const OverflowSafeSignedAPInt &V1,
+                        bool IsMin) -> std::optional<APInt> {
+    if (V0 && V1)
+      return IsMin ? APIntOps::smin(*V0, *V1) : APIntOps::smax(*V0, *V1);
     if (V0)
-      Vec.push_back(*V0);
+      return *V0;
     if (V1)
-      Vec.push_back(*V1);
-    return Vec;
+      return *V1;
+    return std::nullopt;
   };
 
-  SmallVector<APInt, 2> TLVec = CreateVec(TL0, TL1);
-  SmallVector<APInt, 2> TUVec = CreateVec(TU0, TU1);
-
   LLVM_DEBUG(dbgs() << "\t    TA = " << TA << "\n");
   LLVM_DEBUG(dbgs() << "\t    TB = " << TB << "\n");
 
-  if (TLVec.empty() || TUVec.empty())
+  std::optional<APInt> OptTL = GetMaxOrMin(TL0, TL1, false);
+  std::optional<APInt> OptTU = GetMaxOrMin(TU0, TU1, true);
+  if (!OptTL || !OptTU)
     return false;
-  TL = APIntOps::smax(TLVec.front(), TLVec.back());
-  TU = APIntOps::smin(TUVec.front(), TUVec.back());
+
+  TL = std::move(*OptTL);
+  TU = std::move(*OptTU);
   LLVM_DEBUG(dbgs() << "\t    TL = " << TL << "\n");
   LLVM_DEBUG(dbgs() << "\t    TU = " << TU << "\n");
 
@@ -2088,23 +2090,25 @@ bool DependenceInfo::exactRDIVtest(const SCEV *SrcCoeff, const SCEV *DstCoeff,
   LLVM_DEBUG(dbgs() << "\t    TA = " << TA << "\n");
   LLVM_DEBUG(dbgs() << "\t    TB = " << TB << "\n");
 
-  auto CreateVec = [](const OverflowSafeSignedAPInt &V0,
-                      const OverflowSafeSignedAPInt &V1) {
-    SmallVector<APInt, 2> Vec;
+  auto GetMaxOrMin = [](const OverflowSafeSignedAPInt &V0,
+                        const OverflowSafeSignedAPInt &V1,
+                        bool IsMin) -> std::optional<APInt> {
+    if (V0 && V1)
+      return IsMin ? APIntOps::smin(*V0, *V1) : APIntOps::smax(*V0, *V1);
     if (V0)
-      Vec.push_back(*V0);
+      return *V0;
     if (V1)
-      Vec.push_back(*V1);
-    return Vec;
+      return *V1;
+    return std::nullopt;
   };
 
-  SmallVector<APInt, 2> TLVec = CreateVec(TL0, TL1);
-  SmallVector<APInt, 2> TUVec = CreateVec(TU0, TU1);
-  if (TLVec.empty() || TUVec.empty())
+  std::optional<APInt> OptTL = GetMaxOrMin(TL0, TL1, false);
+  std::optional<APInt> OptTU = GetMaxOrMin(TU0, TU1, true);
+  if (!OptTL || !OptTU)
     return false;
 
-  TL = APIntOps::smax(TLVec.front(), TLVec.back());
-  TU = APIntOps::smin(TUVec.front(), TUVec.back());
+  TL = std::move(*OptTL);
+  TU = std::move(*OptTU);
   LLVM_DEBUG(dbgs() << "\t    TL = " << TL << "\n");
   LLVM_DEBUG(dbgs() << "\t    TU = " << TU << "\n");