Add testcase for this:

(3) Do not reduce element sizes of small power of two:

  char s[10];
  for (i)
    ...s[i] ...

when the indvar is not eliminable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20502 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/Transforms/LoopStrengthReduce/dont_reduce_bytes.ll b/test/Transforms/LoopStrengthReduce/dont_reduce_bytes.ll
new file mode 100644 (file)
index 0000000..4a2579f
--- /dev/null
+++ b/test/Transforms/LoopStrengthReduce/dont_reduce_bytes.ll
@@ -0,0 +1,21 @@
+; Don't reduce the byte access to P[i], at least not on targets that 
+; support an efficient 'mem[r1+r2]' addressing mode.
+
+; RUN: llvm-as < %s | opt -loop-reduce | llvm-dis | grep 'getelementptr.*PTR.*INDVAR'
+
+declare bool %pred(int)
+
+void %test(sbyte* %PTR) {
+       br label %Loop
+Loop:
+       %INDVAR = phi int [0, %0], [%INDVAR2, %Loop]
+
+       %STRRED = getelementptr sbyte* %PTR, int %INDVAR
+       store sbyte 0, sbyte* %STRRED
+
+       %INDVAR2 = add int %INDVAR, 1
+       %cond = call bool %pred(int %INDVAR2)  ;; cannot eliminate indvar
+       br bool %cond, label %Loop, label %Out
+Out:
+       ret void
+}