[llvm] 30b5c3f - [Local] Emit nsw for inbounds offset calculation

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2020-11-13T18:39:46+01:00
New Revision: 30b5c3f3a647ce9c5d3d2db5439592f9f00697c7

URL: https://github.com/llvm/llvm-project/commit/30b5c3f3a647ce9c5d3d2db5439592f9f00697c7
DIFF: https://github.com/llvm/llvm-project/commit/30b5c3f3a647ce9c5d3d2db5439592f9f00697c7.diff

LOG: [Local] Emit nsw for inbounds offset calculation

In line with D90708, we can use nsw for the inbounds offset
calculation -- the muls were already using nsw, but the adds were
not.

Added: 
    

Modified: 
    llvm/include/llvm/Analysis/Utils/Local.h
    llvm/test/Transforms/InstCombine/sub-gep.ll
    llvm/test/Transforms/InstCombine/sub.ll

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Analysis/Utils/Local.h b/llvm/include/llvm/Analysis/Utils/Local.h
index f8892c85e1458..bd82b34165d66 100644
--- a/llvm/include/llvm/Analysis/Utils/Local.h
+++ b/llvm/include/llvm/Analysis/Utils/Local.h
@@ -90,7 +90,8 @@ Value *EmitGEPOffset(IRBuilderTy *Builder, const DataLayout &DL, User *GEP,
     }
 
     if (Result)
-      Result = Builder->CreateAdd(Result, Offset, GEP->getName().str()+".offs");
+      Result = Builder->CreateAdd(Result, Offset, GEP->getName().str()+".offs",
+                                  false /*NUW*/, isInBounds /*NSW*/);
     else
       Result = Offset;
   }

diff  --git a/llvm/test/Transforms/InstCombine/sub-gep.ll b/llvm/test/Transforms/InstCombine/sub-gep.ll
index 47dd0ce72f838..9868ed1cdf575 100644
--- a/llvm/test/Transforms/InstCombine/sub-gep.ll
+++ b/llvm/test/Transforms/InstCombine/sub-gep.ll
@@ -143,8 +143,8 @@ define i64 @test_inbounds_nuw_multi_index([0 x [2 x i32]]* %base, i64 %idx, i64
 ; CHECK-LABEL: @test_inbounds_nuw_multi_index(
 ; CHECK-NEXT:    [[P2_IDX:%.*]] = shl nsw i64 [[IDX:%.*]], 3
 ; CHECK-NEXT:    [[P2_IDX1:%.*]] = shl nsw i64 [[IDX2:%.*]], 2
-; CHECK-NEXT:    [[P2_OFFS2:%.*]] = add i64 [[P2_IDX]], [[P2_IDX1]]
-; CHECK-NEXT:    ret i64 [[P2_OFFS2]]
+; CHECK-NEXT:    [[P2_OFFS:%.*]] = add nsw i64 [[P2_IDX]], [[P2_IDX1]]
+; CHECK-NEXT:    ret i64 [[P2_OFFS]]
 ;
   %p1 = getelementptr inbounds [0 x [2 x i32]], [0 x [2 x i32]]* %base, i64 0, i64 0, i64 0
   %p2 = getelementptr inbounds [0 x [2 x i32]], [0 x [2 x i32]]* %base, i64 0, i64 %idx, i64 %idx2

diff  --git a/llvm/test/Transforms/InstCombine/sub.ll b/llvm/test/Transforms/InstCombine/sub.ll
index 3e9c066dfbf3a..d9c67d0568f74 100644
--- a/llvm/test/Transforms/InstCombine/sub.ll
+++ b/llvm/test/Transforms/InstCombine/sub.ll
@@ -1075,8 +1075,8 @@ define i64 @test58([100 x [100 x i8]]* %foo, i64 %i, i64 %j) {
 ; "%sub = i64 %i, %j, ret i64 %sub"
 ; gep1 and gep2 have only one use
 ; CHECK-LABEL: @test58(
-; CHECK-NEXT:    [[GEP1_OFFS:%.*]] = add i64 [[I:%.*]], 4200
-; CHECK-NEXT:    [[GEP2_OFFS:%.*]] = add i64 [[J:%.*]], 4200
+; CHECK-NEXT:    [[GEP1_OFFS:%.*]] = add nsw i64 [[I:%.*]], 4200
+; CHECK-NEXT:    [[GEP2_OFFS:%.*]] = add nsw i64 [[J:%.*]], 4200
 ; CHECK-NEXT:    [[GEPDIFF:%.*]] = sub i64 [[GEP1_OFFS]], [[GEP2_OFFS]]
 ; CHECK-NEXT:    ret i64 [[GEPDIFF]]
 ;