[PATCH] D35035: [InstCombine] Prevent memcpy generation for small data size

[DIVYA SHANMUGHAN via Phabricator via llvm-commits]

DIVYA added a comment.

**TESTCASE1**
Before applying the patch

define void @foo(i8* %a, i8* %b) local_unnamed_addr #0 {
entry:

  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %a, i8* %b, i64 16, i32 1, i1 false)
  ret void

}

After Applying the patch

define void @foo(i8* %a, i8* %b) local_unnamed_addr #0 {
entry:

  %0 = bitcast i8* %b to i128*
  %1 = bitcast i8* %a to i128*
  %2 = load i128, i128* %0, align 1
  store i128 %2, i128* %1, align 1
  ret void

}

TESTCASE2

Before Applying the patch

  %0 = bitcast i32* %add.ptr to i8*
  %add.ptr3 = getelementptr inbounds [16 x i32], [16 x i32]* @b, i64 0, i64 %idx.ext
  %1 = bitcast i32* %add.ptr3 to i8*
  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %0, i8* %1, i64 16, i32 4, i1 false)
  %inc = add nsw i32 %i.0, 1

After Applying the patch

  %0 = bitcast i32* %add.ptr3 to i128*
  %1 = bitcast i32* %add.ptr to i128*
  %2 = load i128, i128* %0, align 16
  store i128 %2, i128* %1, align 4


https://reviews.llvm.org/D35035