Add pthread_self function prototype and make it speculatable.

Summary: This allows pthread_self to be pulled out of a loop by LICM.

Reviewers: hfinkel, arsenm, davide

Reviewed By: davide

Subscribers: davide, wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D32782

llvm-svn: 303495

1 files changed, 38 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LICM/pthread.ll b/llvm/test/Transforms/LICM/pthread.ll
new file mode 100644
index 00000000000..6a7aa499b5a
--- /dev/null
+++ b/llvm/test/Transforms/LICM/pthread.ll
@@ -0,0 +1,38 @@
+; RUN: opt < %s -S  -inferattrs -licm | FileCheck %s
+
+; CHECK-LABEL: define void @pthread_self_safe(
+; CHECK-NEXT: call i64 @pthread_self() 
+define void @pthread_self_safe(i32) {
+  br label %2
+
+; <label>:2:                                      ; preds = %7, %1
+  %idx = phi i32 [ 0, %1 ], [ %8, %7 ]
+  %3 = icmp slt i32 %idx, %0
+  br i1 %3, label %4, label %9
+
+; <label>:4:                                      ; preds = %2
+  call void @external_func_that_could_do_anything()
+  %5 = call i64 @pthread_self() #1
+  %6 = trunc i64 %5 to i32
+  call void @use_pthread_self(i32 %6)
+  br label %7
+
+; <label>:7:                                      ; preds = %4
+  %8 = add nsw i32 %idx, 1
+  br label %2
+
+; <label>:9:                                      ; preds = %2
+  ret void
+}
+
+; CHECK: declare i64 @pthread_self() #0
+; CHECK: attributes #0 = { nounwind readnone speculatable }
+; Function Attrs: nounwind readnone
+declare i64 @pthread_self() #1
+
+declare void @external_func_that_could_do_anything()
+
+declare void @use_pthread_self(i32)
+
+attributes #1 = { nounwind readnone }
+