[PATCH] D108601: [SCEV] Infer nuw from nw for addrecs

[Philip Reames via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGec8d87e9f562: [SCEV] Infer nuw from nw for addrecs (authored by reames).

Changed prior to commit:
  https://reviews.llvm.org/D108601?vs=368460&id=368467#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D108601/new/

https://reviews.llvm.org/D108601

Files:
  llvm/lib/Analysis/ScalarEvolution.cpp
  llvm/test/Analysis/ScalarEvolution/ptrtoint.ll


Index: llvm/test/Analysis/ScalarEvolution/ptrtoint.ll
===================================================================
--- llvm/test/Analysis/ScalarEvolution/ptrtoint.ll
+++ llvm/test/Analysis/ScalarEvolution/ptrtoint.ll
@@ -386,7 +386,7 @@
 ; X64-NEXT:    %i9 = ptrtoint i8* %i7 to i64
 ; X64-NEXT:    --> {(ptrtoint i8* %arg to i64),+,1}<nuw><%bb6> U: full-set S: full-set Exits: (-1 + (ptrtoint i8* %arg1 to i64)) LoopDispositions: { %bb6: Computable }
 ; X64-NEXT:    %i10 = sub i64 %i9, %i4
-; X64-NEXT:    --> {0,+,1}<nw><%bb6> U: full-set S: full-set Exits: (-1 + (-1 * (ptrtoint i8* %arg to i64)) + (ptrtoint i8* %arg1 to i64)) LoopDispositions: { %bb6: Computable }
+; X64-NEXT:    --> {0,+,1}<nuw><%bb6> U: full-set S: full-set Exits: (-1 + (-1 * (ptrtoint i8* %arg to i64)) + (ptrtoint i8* %arg1 to i64)) LoopDispositions: { %bb6: Computable }
 ; X64-NEXT:    %i11 = getelementptr inbounds i8, i8* %arg2, i64 %i10
 ; X64-NEXT:    --> {%arg2,+,1}<nw><%bb6> U: full-set S: full-set Exits: (-1 + (-1 * (ptrtoint i8* %arg to i64)) + (ptrtoint i8* %arg1 to i64) + %arg2) LoopDispositions: { %bb6: Computable }
 ; X64-NEXT:    %i12 = load i8, i8* %i11, align 1
@@ -413,7 +413,7 @@
 ; X32-NEXT:    %i9 = ptrtoint i8* %i7 to i64
 ; X32-NEXT:    --> {(zext i32 (ptrtoint i8* %arg to i32) to i64),+,1}<nuw><%bb6> U: [0,8589934591) S: [0,8589934591) Exits: ((zext i32 (-1 + (-1 * (ptrtoint i8* %arg to i32)) + (ptrtoint i8* %arg1 to i32)) to i64) + (zext i32 (ptrtoint i8* %arg to i32) to i64)) LoopDispositions: { %bb6: Computable }
 ; X32-NEXT:    %i10 = sub i64 %i9, %i4
-; X32-NEXT:    --> {0,+,1}<nw><%bb6> U: [0,4294967296) S: [0,4294967296) Exits: (zext i32 (-1 + (-1 * (ptrtoint i8* %arg to i32)) + (ptrtoint i8* %arg1 to i32)) to i64) LoopDispositions: { %bb6: Computable }
+; X32-NEXT:    --> {0,+,1}<nuw><%bb6> U: [0,4294967296) S: [0,4294967296) Exits: (zext i32 (-1 + (-1 * (ptrtoint i8* %arg to i32)) + (ptrtoint i8* %arg1 to i32)) to i64) LoopDispositions: { %bb6: Computable }
 ; X32-NEXT:    %i11 = getelementptr inbounds i8, i8* %arg2, i64 %i10
 ; X32-NEXT:    --> {%arg2,+,1}<%bb6> U: full-set S: full-set Exits: (-1 + (-1 * (ptrtoint i8* %arg to i32)) + (ptrtoint i8* %arg1 to i32) + %arg2) LoopDispositions: { %bb6: Computable }
 ; X32-NEXT:    %i12 = load i8, i8* %i11, align 1
@@ -471,7 +471,7 @@
 ; X64-NEXT:    %i9 = ptrtoint i32* %i7 to i64
 ; X64-NEXT:    --> {(ptrtoint i32* %arg to i64),+,4}<nuw><%bb6> U: full-set S: full-set Exits: ((4 * ((-4 + (-1 * (ptrtoint i32* %arg to i64)) + (ptrtoint i32* %arg1 to i64)) /u 4))<nuw> + (ptrtoint i32* %arg to i64)) LoopDispositions: { %bb6: Computable }
 ; X64-NEXT:    %i10 = sub i64 %i9, %i4
-; X64-NEXT:    --> {0,+,4}<nw><%bb6> U: [0,-3) S: [-9223372036854775808,9223372036854775805) Exits: (4 * ((-4 + (-1 * (ptrtoint i32* %arg to i64)) + (ptrtoint i32* %arg1 to i64)) /u 4))<nuw> LoopDispositions: { %bb6: Computable }
+; X64-NEXT:    --> {0,+,4}<nuw><%bb6> U: [0,-3) S: [-9223372036854775808,9223372036854775805) Exits: (4 * ((-4 + (-1 * (ptrtoint i32* %arg to i64)) + (ptrtoint i32* %arg1 to i64)) /u 4))<nuw> LoopDispositions: { %bb6: Computable }
 ; X64-NEXT:    %i11 = ashr exact i64 %i10, 2
 ; X64-NEXT:    --> %i11 U: [-2305843009213693952,2305843009213693952) S: [-2305843009213693952,2305843009213693952) Exits: <<Unknown>> LoopDispositions: { %bb6: Variant }
 ; X64-NEXT:    %i12 = getelementptr inbounds i32, i32* %arg2, i64 %i11
@@ -500,7 +500,7 @@
 ; X32-NEXT:    %i9 = ptrtoint i32* %i7 to i64
 ; X32-NEXT:    --> {(zext i32 (ptrtoint i32* %arg to i32) to i64),+,4}<nuw><%bb6> U: [0,8589934588) S: [0,8589934588) Exits: ((zext i32 (ptrtoint i32* %arg to i32) to i64) + (4 * ((zext i32 (-4 + (-1 * (ptrtoint i32* %arg to i32)) + (ptrtoint i32* %arg1 to i32)) to i64) /u 4))<nuw><nsw>) LoopDispositions: { %bb6: Computable }
 ; X32-NEXT:    %i10 = sub i64 %i9, %i4
-; X32-NEXT:    --> {0,+,4}<nw><%bb6> U: [0,4294967293) S: [0,4294967293) Exits: (4 * ((zext i32 (-4 + (-1 * (ptrtoint i32* %arg to i32)) + (ptrtoint i32* %arg1 to i32)) to i64) /u 4))<nuw><nsw> LoopDispositions: { %bb6: Computable }
+; X32-NEXT:    --> {0,+,4}<nuw><%bb6> U: [0,4294967293) S: [0,4294967293) Exits: (4 * ((zext i32 (-4 + (-1 * (ptrtoint i32* %arg to i32)) + (ptrtoint i32* %arg1 to i32)) to i64) /u 4))<nuw><nsw> LoopDispositions: { %bb6: Computable }
 ; X32-NEXT:    %i11 = ashr exact i64 %i10, 2
 ; X32-NEXT:    --> %i11 U: [-2147483648,2147483648) S: [-2147483648,2147483648) Exits: <<Unknown>> LoopDispositions: { %bb6: Variant }
 ; X32-NEXT:    %i12 = getelementptr inbounds i32, i32* %arg2, i64 %i11
Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -2390,6 +2390,13 @@
     }
   }
 
+  // <0,+,nonnegative><nw> is also nuw
+  // TODO: Add corresponding nsw case
+  if (Type == scAddRecExpr && ScalarEvolution::hasFlags(Flags, SCEV::FlagNW) &&
+      !ScalarEvolution::hasFlags(Flags, SCEV::FlagNUW) && Ops.size() == 2 &&
+      Ops[0]->isZero() && IsKnownNonNegative(Ops[1]))
+    Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
+
   return Flags;
 }
 


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