Fix a bug in the code that checks if we can vectorize loops while using dynamic

memory bound checks.  Before the fix we were able to vectorize this loop from
the Livermore Loops benchmark:

for ( k=1 ; k<n ; k++ )
  x[k] = x[k-1] + y[k];



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170811 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 110 insertions, 0 deletions

diff --git a/test/Transforms/LoopVectorize/same-base-access.ll b/test/Transforms/LoopVectorize/same-base-access.ll
new file mode 100644
index 0000000000..f9ef32e492
--- /dev/null
+++ b/test/Transforms/LoopVectorize/same-base-access.ll
@@ -0,0 +1,110 @@
+; RUN: opt < %s  -loop-vectorize -force-vector-width=4 -dce -instcombine -licm -S -enable-if-conversion | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.9.0"
+
+; This is kernel11 from "LivermoreLoops". We can't vectorize it because we
+; access both x[k] and x[k-1].
+;
+; void kernel11(double *x, double *y, int n) {
+;   for ( int k=1 ; k<n ; k++ )
+;     x[k] = x[k-1] + y[k];
+; }
+
+; CHECK: @kernel11
+; CHECK-NOT: <4 x double>
+; CHECK: ret
+define i32 @kernel11(double* %x, double* %y, i32 %n) nounwind uwtable ssp {
+  %1 = alloca double*, align 8
+  %2 = alloca double*, align 8
+  %3 = alloca i32, align 4
+  %k = alloca i32, align 4
+  store double* %x, double** %1, align 8
+  store double* %y, double** %2, align 8
+  store i32 %n, i32* %3, align 4
+  store i32 1, i32* %k, align 4
+  br label %4
+
+; <label>:4                                       ; preds = %25, %0
+  %5 = load i32* %k, align 4
+  %6 = load i32* %3, align 4
+  %7 = icmp slt i32 %5, %6
+  br i1 %7, label %8, label %28
+
+; <label>:8                                       ; preds = %4
+  %9 = load i32* %k, align 4
+  %10 = sub nsw i32 %9, 1
+  %11 = sext i32 %10 to i64
+  %12 = load double** %1, align 8
+  %13 = getelementptr inbounds double* %12, i64 %11
+  %14 = load double* %13, align 8
+  %15 = load i32* %k, align 4
+  %16 = sext i32 %15 to i64
+  %17 = load double** %2, align 8
+  %18 = getelementptr inbounds double* %17, i64 %16
+  %19 = load double* %18, align 8
+  %20 = fadd double %14, %19
+  %21 = load i32* %k, align 4
+  %22 = sext i32 %21 to i64
+  %23 = load double** %1, align 8
+  %24 = getelementptr inbounds double* %23, i64 %22
+  store double %20, double* %24, align 8
+  br label %25
+
+; <label>:25                                      ; preds = %8
+  %26 = load i32* %k, align 4
+  %27 = add nsw i32 %26, 1
+  store i32 %27, i32* %k, align 4
+  br label %4
+
+; <label>:28                                      ; preds = %4
+  ret i32 0
+}
+
+
+
+; We don't vectorize this function because A[i*7] is scalarized, and the
+; different scalars can in theory wrap around and overwrite other scalar
+; elements. At the moment we only allow read/write access to arrays
+; that are consecutive.
+; 
+; void foo(int *a) {
+;   for (int i=0; i<256; ++i) {
+;     int x = a[i*7];
+;     if (x>3)
+;       x = x*x+x*4;
+;     a[i*7] = x+3;
+;   }
+; }
+
+; CHECK: @func2
+; CHECK-NOT: <4 x i32>
+; CHECK: ret
+define i32 @func2(i32* nocapture %a) nounwind uwtable ssp {
+  br label %1
+
+; <label>:1                                       ; preds = %7, %0
+  %indvars.iv = phi i64 [ 0, %0 ], [ %indvars.iv.next, %7 ]
+  %2 = mul nsw i64 %indvars.iv, 7
+  %3 = getelementptr inbounds i32* %a, i64 %2
+  %4 = load i32* %3, align 4
+  %5 = icmp sgt i32 %4, 3
+  br i1 %5, label %6, label %7
+
+; <label>:6                                       ; preds = %1
+  %tmp = add i32 %4, 4
+  %tmp1 = mul i32 %tmp, %4
+  br label %7
+
+; <label>:7                                       ; preds = %6, %1
+  %x.0 = phi i32 [ %tmp1, %6 ], [ %4, %1 ]
+  %8 = add nsw i32 %x.0, 3
+  store i32 %8, i32* %3, align 4
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, 256
+  br i1 %exitcond, label %9, label %1
+
+; <label>:9                                       ; preds = %7
+  ret i32 0
+}