[SCEV] Introduce SCEVUse, use it instead of const SCEV * (NFCI). (#91961)

This patch introduces SCEVUse, which is a tagged pointer containing the
used const SCEV *, plus extra bits to store NUW/NSW flags that are only
valid at the specific use.

This was suggested by @nikic as an alternative
to https://github.com/llvm/llvm-project/pull/90742.

This patch just updates most SCEV infrastructure to operate on SCEVUse
instead of const SCEV *. It does not introduce any code that makes use
of the use-specific flags yet which I'll share as follow-ups.

Compile-time impact: https://llvm-compile-time-tracker.com/compare.php?from=ee34eb6edccdebc2a752ffecdde5faae6b0d5593&to=5a7727d7819414d2acbc5b6ab740f0fc2363e842&stat=instructions%3Au

1 files changed, 16 insertions, 16 deletions

diff --git a/polly/lib/Support/ScopHelper.cpp b/polly/lib/Support/ScopHelper.cpp
index fe9b8bb1ffea..fb80edcf1d30 100644
--- a/polly/lib/Support/ScopHelper.cpp
+++ b/polly/lib/Support/ScopHelper.cpp
@@ -243,7 +243,7 @@ struct ScopExpander final : SCEVVisitor<ScopExpander, const SCEV *> {
 
   explicit ScopExpander(const Region &R, ScalarEvolution &SE, Function *GenFn,
                         ScalarEvolution &GenSE, const char *Name,
-                        ValueMapT *VMap, LoopToScevMapT *LoopMap,
+                        ValueMapT *VMap, polly::LoopToScevMapT *LoopMap,
                         BasicBlock *RTCBB)
       : Expander(GenSE, Name, /*PreserveLCSSA=*/false), Name(Name), R(R),
         VMap(VMap), LoopMap(LoopMap), RTCBB(RTCBB), GenSE(GenSE), GenFn(GenFn) {
@@ -272,7 +272,7 @@ private:
   const char *Name;
   const Region &R;
   ValueMapT *VMap;
-  LoopToScevMapT *LoopMap;
+  polly::LoopToScevMapT *LoopMap;
   BasicBlock *RTCBB;
   DenseMap<const SCEV *, const SCEV *> SCEVCache;
 
@@ -389,50 +389,50 @@ private:
     return GenSE.getUDivExpr(visit(E->getLHS()), RHSScev);
   }
   const SCEV *visitAddExpr(const SCEVAddExpr *E) {
-    SmallVector<const SCEV *, 4> NewOps;
+    SmallVector<SCEVUse, 4> NewOps;
     for (const SCEV *Op : E->operands())
       NewOps.push_back(visit(Op));
     return GenSE.getAddExpr(NewOps);
   }
   const SCEV *visitMulExpr(const SCEVMulExpr *E) {
-    SmallVector<const SCEV *, 4> NewOps;
+    SmallVector<SCEVUse, 4> NewOps;
     for (const SCEV *Op : E->operands())
       NewOps.push_back(visit(Op));
     return GenSE.getMulExpr(NewOps);
   }
   const SCEV *visitUMaxExpr(const SCEVUMaxExpr *E) {
-    SmallVector<const SCEV *, 4> NewOps;
-    for (const SCEV *Op : E->operands())
+    SmallVector<SCEVUse, 4> NewOps;
+    for (SCEVUse Op : E->operands())
       NewOps.push_back(visit(Op));
     return GenSE.getUMaxExpr(NewOps);
   }
   const SCEV *visitSMaxExpr(const SCEVSMaxExpr *E) {
-    SmallVector<const SCEV *, 4> NewOps;
-    for (const SCEV *Op : E->operands())
+    SmallVector<SCEVUse, 4> NewOps;
+    for (SCEVUse Op : E->operands())
       NewOps.push_back(visit(Op));
     return GenSE.getSMaxExpr(NewOps);
   }
   const SCEV *visitUMinExpr(const SCEVUMinExpr *E) {
-    SmallVector<const SCEV *, 4> NewOps;
-    for (const SCEV *Op : E->operands())
+    SmallVector<SCEVUse, 4> NewOps;
+    for (SCEVUse Op : E->operands())
       NewOps.push_back(visit(Op));
     return GenSE.getUMinExpr(NewOps);
   }
   const SCEV *visitSMinExpr(const SCEVSMinExpr *E) {
-    SmallVector<const SCEV *, 4> NewOps;
-    for (const SCEV *Op : E->operands())
+    SmallVector<SCEVUse, 4> NewOps;
+    for (SCEVUse Op : E->operands())
       NewOps.push_back(visit(Op));
     return GenSE.getSMinExpr(NewOps);
   }
   const SCEV *visitSequentialUMinExpr(const SCEVSequentialUMinExpr *E) {
-    SmallVector<const SCEV *, 4> NewOps;
-    for (const SCEV *Op : E->operands())
+    SmallVector<SCEVUse, 4> NewOps;
+    for (SCEVUse Op : E->operands())
       NewOps.push_back(visit(Op));
     return GenSE.getUMinExpr(NewOps, /*Sequential=*/true);
   }
   const SCEV *visitAddRecExpr(const SCEVAddRecExpr *E) {
-    SmallVector<const SCEV *, 4> NewOps;
-    for (const SCEV *Op : E->operands())
+    SmallVector<SCEVUse, 4> NewOps;
+    for (SCEVUse Op : E->operands())
       NewOps.push_back(visit(Op));
 
     const Loop *L = E->getLoop();