Add a minor optimization: if we haven't changed the operands of an

add, there is no need to scan the world to find the same add again.
This invalidates the previous testcase, which wasn't wonderful anyway,
because it needed a run of instcombine to permute the use-lists in 
just the right way to before GVN was run (so it was really fragile).
Not a big loss.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90973 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 4 insertions, 66 deletions

diff --git a/lib/Analysis/PHITransAddr.cpp b/lib/Analysis/PHITransAddr.cpp
index a1b2afbaf7..07e291971a 100644
--- a/lib/Analysis/PHITransAddr.cpp
+++ b/lib/Analysis/PHITransAddr.cpp
@@ -275,6 +275,10 @@ Value *PHITransAddr::PHITranslateSubExpr(Value *V, BasicBlock *CurBB,
       RemoveInstInputs(LHS, InstInputs);
       return AddAsInput(Res);
     }
+
+    // If we didn't modify the add, just return it.
+    if (LHS == Inst->getOperand(0) && RHS == Inst->getOperand(1))
+      return Inst;
     
     // Otherwise, see if we have this add available somewhere.
     for (Value::use_iterator UI = LHS->use_begin(), E = LHS->use_end();
diff --git a/test/Transforms/GVN/crash-2.ll b/test/Transforms/GVN/crash-2.ll
deleted file mode 100644
index ee1ab6d6c6..0000000000
--- a/test/Transforms/GVN/crash-2.ll
+++ /dev/null
@@ -1,66 +0,0 @@
-; RUN: opt -instcombine -gvn -S %s
-; PR5733
-target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
-target triple = "i686-linux-gnu"
-
-@ff_cropTbl = external global [2304 x i8]         ; <[2304 x i8]*> [#uses=1]
-
-define void @ff_pred8x8_plane_c(i8* nocapture %src, i32 %stride) nounwind {
-entry:
-  br i1 true, label %bb.nph41, label %for.end
-
-
-bb.nph41:                                         ; preds = %entry
-  %sub.ptr.neg37 = sub i32 0, %stride             ; <i32> [#uses=1]
-  %tmp55 = add i32 %sub.ptr.neg37, -1             ; <i32> [#uses=1]
-  %tmp73 = add i32 %stride, -1                    ; <i32> [#uses=2]
-  %sub.ptr38 = getelementptr i8* %src, i32 %tmp73 ; <i8*> [#uses=1]
-  %tmp60 = load i8* %sub.ptr38                    ; <i8> [#uses=1]
-  %conv61 = zext i8 %tmp60 to i32                 ; <i32> [#uses=1]
-  %sub62 = sub i32 0, %conv61                     ; <i32> [#uses=1]
-  %mul63 = mul i32 %sub62, 2                      ; <i32> [#uses=1]
-  %add65 = add nsw i32 %mul63, 0                  ; <i32> [#uses=1]
-  %tmp71.2 = mul i32 2, %stride                   ; <i32> [#uses=1]
-  %tmp72.2 = sub i32 0, %tmp71.2                  ; <i32> [#uses=1]
-  %tmp74.2 = add i32 %tmp72.2, %tmp73             ; <i32> [#uses=1]
-  %sub.ptr38.2 = getelementptr i8* %src, i32 %tmp74.2 ; <i8*> [#uses=1]
-  %tmp60.2 = load i8* %sub.ptr38.2                ; <i8> [#uses=1]
-  %conv61.2 = zext i8 %tmp60.2 to i32             ; <i32> [#uses=1]
-  %sub62.2 = sub i32 0, %conv61.2                 ; <i32> [#uses=1]
-  %mul63.2 = mul i32 %sub62.2, 4                  ; <i32> [#uses=1]
-  %add65.2 = add nsw i32 %mul63.2, %add65       ; <i32> [#uses=1]
-  %scevgep = getelementptr i8* %src, i32 %tmp55   ; <i8*> [#uses=1]
-  br label %for.end
-
-for.end:                                          ; preds = %for.cond.2, %entry
-  %V.0.lcssa = phi i32 [ %add65.2, %bb.nph41 ], [ 0, %entry ] ; <i32> [#uses=1]
-  %src2.0.lcssa = phi i8* [ %scevgep, %bb.nph41 ], [ null, %entry ] ; <i8*> [#uses=1]
-  %mul71 = mul i32 %V.0.lcssa, 17                 ; <i32> [#uses=1]
-  %add72 = add nsw i32 %mul71, 16                 ; <i32> [#uses=1]
-  %shr73 = ashr i32 %add72, 5                     ; <i32> [#uses=1]
-  br i1 true, label %bb.nph, label %for.end181
-
-bb.nph:                                           ; preds = %for.end
-  %arrayidx79 = getelementptr inbounds i8* %src2.0.lcssa, i32 8 ; <i8*> [#uses=1]
-  %tmp80 = load i8* %arrayidx79                   ; <i8> [#uses=1]
-  %tmp9 = mul i32 %shr73, -3                      ; <i32> [#uses=1]
-  %tmp11 = zext i8 %tmp80 to i32                  ; <i32> [#uses=1]
-  %tmp12 = add i32 0, %tmp11                      ; <i32> [#uses=1]
-  %tmp13 = mul i32 %tmp12, 16                     ; <i32> [#uses=1]
-  %tmp38 = add i32 %tmp9, %tmp13                  ; <i32> [#uses=1]
-  %tmp39 = add i32 %tmp38, 16                     ; <i32> [#uses=1]
-  br label %for.body94
-
-for.body94:                                       ; preds = %bb.nph, %for.cond90
-  %add129 = add i32 0, %tmp39                     ; <i32> [#uses=1]
-  %shr130 = ashr i32 %add129, 5                   ; <i32> [#uses=1]
-  %.sum4 = add i32 %shr130, 1024                  ; <i32> [#uses=1]
-  %arrayidx132 = getelementptr inbounds [2304 x i8]* @ff_cropTbl, i32 0, i32 %.sum4 ; <i8*> [#uses=1]
-  %tmp133 = load i8* %arrayidx132                 ; <i8> [#uses=1]
-  store i8 %tmp133, i8* undef
-  br label %for.body94
-
-for.end181:                                       ; preds = %for.cond90.for.end181_crit_edge, %for.end
-  ret void
-
-}