Fix strange logic in CollectIVUsers used to determine whether all uses are

addresses, part 1. This fixes an obvious logic bug. Previously if the only
in-loop use is a PHI, it would return AllUsesAreAddresses as true.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65178 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 52 insertions, 1 deletions

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index a52b7d0f1c..d18a008fef 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -1439,6 +1439,7 @@ SCEVHandle LoopStrengthReduce::CollectIVUsers(const SCEVHandle &Stride,
   // fields of the BasedUsers.  We do this so that it increases the commonality
   // of the remaining uses.
   unsigned NumPHI = 0;
+  bool HasAddress = false;
   for (unsigned i = 0, e = UsersToProcess.size(); i != e; ++i) {
     // If the user is not in the current loop, this means it is using the exit
     // value of the IV.  Do not put anything in the base, make sure it's all in
@@ -1449,7 +1450,6 @@ SCEVHandle LoopStrengthReduce::CollectIVUsers(const SCEVHandle &Stride,
       UsersToProcess[i].Base = 
         SE->getIntegerSCEV(0, UsersToProcess[i].Base->getType());
     } else {
-
       // Addressing modes can be folded into loads and stores.  Be careful that
       // the store is through the expression, not of the expression though.
       bool isPHI = false;
@@ -1462,6 +1462,9 @@ SCEVHandle LoopStrengthReduce::CollectIVUsers(const SCEVHandle &Stride,
 
       // Not all uses are outside the loop.
       AllUsesAreOutsideLoop = false; 
+
+      if (isAddress)
+        HasAddress = true;
      
       // If this use isn't an address, then not all uses are addresses.
       if (!isAddress && !isPHI)
@@ -1478,6 +1481,10 @@ SCEVHandle LoopStrengthReduce::CollectIVUsers(const SCEVHandle &Stride,
   if (NumPHI > 1)
     AllUsesAreAddresses = false;
 
+  // There are no in-loop address uses.
+  if (AllUsesAreAddresses && (!HasAddress && !AllUsesAreOutsideLoop))
+    AllUsesAreAddresses = false;
+
   return CommonExprs;
 }
 
diff --git a/test/CodeGen/X86/loop-strength-reduce7.ll b/test/CodeGen/X86/loop-strength-reduce7.ll
new file mode 100644
index 0000000000..b6a130a861
--- /dev/null
+++ b/test/CodeGen/X86/loop-strength-reduce7.ll
@@ -0,0 +1,44 @@
+; RUN: llvm-as < %s | llc -march=x86 | not grep imul
+
+target triple = "i386-apple-darwin9.6"
+	%struct.III_psy_xmin = type { [22 x double], [13 x [3 x double]] }
+	%struct.III_scalefac_t = type { [22 x i32], [13 x [3 x i32]] }
+	%struct.gr_info = type { i32, i32, i32, i32, i32, i32, i32, i32, [3 x i32], [3 x i32], i32, i32, i32, i32, i32, i32, i32, i32, i32, i32*, [4 x i32] }
+	%struct.lame_global_flags = type { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i8*, i8*, i32, i32, float, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, float, i32, i32, i32, float, float, float, float, i32, i32, i32, i32, i32, i32, i32, i32 }
+
+define fastcc void @outer_loop(%struct.lame_global_flags* nocapture %gfp, double* nocapture %xr, i32 %targ_bits, double* nocapture %best_noise, %struct.III_psy_xmin* nocapture %l3_xmin, i32* nocapture %l3_enc, %struct.III_scalefac_t* nocapture %scalefac, %struct.gr_info* nocapture %cod_info, i32 %ch) nounwind {
+entry:
+	br label %bb4
+
+bb4:		; preds = %bb4, %entry
+	br i1 true, label %bb5, label %bb4
+
+bb5:		; preds = %bb4
+	br i1 true, label %bb28.i37, label %bb.i4
+
+bb.i4:		; preds = %bb.i4, %bb5
+	br label %bb.i4
+
+bb28.i37:		; preds = %bb33.i47, %bb5
+	%i.1.reg2mem.0.i = phi i32 [ %0, %bb33.i47 ], [ 0, %bb5 ]		; <i32> [#uses=2]
+	%0 = add i32 %i.1.reg2mem.0.i, 1		; <i32> [#uses=2]
+	br label %bb29.i38
+
+bb29.i38:		; preds = %bb33.i47, %bb28.i37
+	%indvar32.i = phi i32 [ %indvar.next33.i, %bb33.i47 ], [ 0, %bb28.i37 ]		; <i32> [#uses=2]
+	%sfb.314.i = add i32 %indvar32.i, 0		; <i32> [#uses=3]
+	%1 = getelementptr [4 x [21 x double]]* null, i32 0, i32 %0, i32 %sfb.314.i		; <double*> [#uses=1]
+	%2 = load double* %1, align 8		; <double> [#uses=0]
+	br i1 false, label %bb30.i41, label %bb33.i47
+
+bb30.i41:		; preds = %bb29.i38
+	%3 = getelementptr %struct.III_scalefac_t* null, i32 0, i32 1, i32 %sfb.314.i, i32 %i.1.reg2mem.0.i		; <i32*> [#uses=1]
+	store i32 0, i32* %3, align 4
+	br label %bb33.i47
+
+bb33.i47:		; preds = %bb30.i41, %bb29.i38
+	%4 = add i32 %sfb.314.i, 1		; <i32> [#uses=1]
+	%phitmp.i46 = icmp ugt i32 %4, 11		; <i1> [#uses=1]
+	%indvar.next33.i = add i32 %indvar32.i, 1		; <i32> [#uses=1]
+	br i1 %phitmp.i46, label %bb28.i37, label %bb29.i38
+}