[LoopVectorizer] give more advice in remark about failure to vectorize call

Something like this is requested by:
https://bugs.llvm.org/show_bug.cgi?id=40265
...and it seems like a common enough case that we should acknowledge it.

Differential Revision: https://reviews.llvm.org/D56551

llvm-svn: 351010

1 files changed, 52 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopVectorize/libcall-remark.ll b/llvm/test/Transforms/LoopVectorize/libcall-remark.ll
new file mode 100644
index 00000000000..a1a7e461c70
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/libcall-remark.ll
@@ -0,0 +1,52 @@
+; RUN: opt -S -loop-vectorize < %s 2>&1 -pass-remarks-analysis=.* | FileCheck %s
+
+; Test the optimization remark emitter for recognition 
+; of a mathlib function vs. an arbitrary function.
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.14.0"
+@data = external local_unnamed_addr global [32768 x float], align 16
+
+; CHECK: loop not vectorized: library call cannot be vectorized
+
+define void @libcall_blocks_vectorization() {
+entry:
+  br label %for.body
+
+for.cond.cleanup:
+  ret void
+
+for.body:
+  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %arrayidx = getelementptr inbounds [32768 x float], [32768 x float]* @data, i64 0, i64 %indvars.iv
+  %t0 = load float, float* %arrayidx, align 4
+  %sqrtf = tail call float @sqrtf(float %t0)
+  store float %sqrtf, float* %arrayidx, align 4
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %exitcond = icmp eq i64 %indvars.iv.next, 32768
+  br i1 %exitcond, label %for.cond.cleanup, label %for.body
+}
+
+; CHECK: loop not vectorized: call instruction cannot be vectorized
+
+define void @arbitrary_call_blocks_vectorization() {
+entry:
+  br label %for.body
+
+for.cond.cleanup:
+  ret void
+
+for.body:
+  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %arrayidx = getelementptr inbounds [32768 x float], [32768 x float]* @data, i64 0, i64 %indvars.iv
+  %t0 = load float, float* %arrayidx, align 4
+  %sqrtf = tail call float @arbitrary(float %t0)
+  store float %sqrtf, float* %arrayidx, align 4
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %exitcond = icmp eq i64 %indvars.iv.next, 32768
+  br i1 %exitcond, label %for.cond.cleanup, label %for.body
+}
+
+declare float @sqrtf(float)
+declare float @arbitrary(float)
+