[LoopVectorize] Use ReplaceInstWithInst() helper where appropriate.

This is mostly an NFC, which increases code readability (instead of
saving old terminator, generating new one in front of old, and deleting
old, we just call a function). However, it would additionaly copy
the debug location from old instruction to replacement, which
would help PR23837.

llvm-svn: 241197
diff --git a/llvm/test/Transforms/LoopVectorize/runtime-check.ll b/llvm/test/Transforms/LoopVectorize/runtime-check.ll
index b1c5d40..1f07d3f 100644
--- a/llvm/test/Transforms/LoopVectorize/runtime-check.ll
+++ b/llvm/test/Transforms/LoopVectorize/runtime-check.ll
@@ -9,30 +9,31 @@
 ;     a[i] = b[i] * 3;
 ; }
 
+;CHECK-LABEL: define i32 @foo
 ;CHECK: for.body.preheader:
-;CHECK: br i1 %cmp.zero, label %middle.block, label %vector.memcheck
+;CHECK: br i1 %cmp.zero, label %middle.block, label %vector.memcheck, !dbg [[BODY_LOC:![0-9]+]]
 ;CHECK: vector.memcheck:
-;CHECK: br i1 %memcheck.conflict, label %middle.block, label %vector.ph
+;CHECK: br i1 %memcheck.conflict, label %middle.block, label %vector.ph, !dbg [[BODY_LOC]]
 ;CHECK: load <4 x float>
 define i32 @foo(float* nocapture %a, float* nocapture %b, i32 %n) nounwind uwtable ssp {
 entry:
-  %cmp6 = icmp sgt i32 %n, 0
-  br i1 %cmp6, label %for.body, label %for.end
+  %cmp6 = icmp sgt i32 %n, 0, !dbg !6
+  br i1 %cmp6, label %for.body, label %for.end, !dbg !6
 
 for.body:                                         ; preds = %entry, %for.body
-  %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
-  %arrayidx = getelementptr inbounds float, float* %b, i64 %indvars.iv
-  %0 = load float, float* %arrayidx, align 4
-  %mul = fmul float %0, 3.000000e+00
-  %arrayidx2 = getelementptr inbounds float, float* %a, i64 %indvars.iv
-  store float %mul, float* %arrayidx2, 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, %n
-  br i1 %exitcond, label %for.end, label %for.body
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ], !dbg !7
+  %arrayidx = getelementptr inbounds float, float* %b, i64 %indvars.iv, !dbg !7
+  %0 = load float, float* %arrayidx, align 4, !dbg !7
+  %mul = fmul float %0, 3.000000e+00, !dbg !7
+  %arrayidx2 = getelementptr inbounds float, float* %a, i64 %indvars.iv, !dbg !7
+  store float %mul, float* %arrayidx2, align 4, !dbg !7
+  %indvars.iv.next = add i64 %indvars.iv, 1, !dbg !7
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32, !dbg !7
+  %exitcond = icmp eq i32 %lftr.wideiv, %n, !dbg !7
+  br i1 %exitcond, label %for.end, label %for.body, !dbg !7
 
 for.end:                                          ; preds = %for.body, %entry
-  ret i32 undef
+  ret i32 undef, !dbg !8
 }
 
 ; Make sure that we try to vectorize loops with a runtime check if the
@@ -62,3 +63,17 @@
 loopexit:
   ret void
 }
+
+; CHECK: [[BODY_LOC]] = !DILocation(line: 101, column: 1, scope: !{{.*}})
+
+!llvm.module.flags = !{!0, !1}
+!0 = !{i32 2, !"Dwarf Version", i32 4}
+!1 = !{i32 2, !"Debug Info Version", i32 3}
+
+!2 = !{}
+!3 = !DISubroutineType(types: !2)
+!4 = !DIFile(filename: "test.cpp", directory: "/tmp")
+!5 = !DISubprogram(name: "foo", scope: !4, file: !4, line: 99, type: !3, isLocal: false, isDefinition: true, scopeLine: 100, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
+!6 = !DILocation(line: 100, column: 1, scope: !5)
+!7 = !DILocation(line: 101, column: 1, scope: !5)
+!8 = !DILocation(line: 102, column: 1, scope: !5)