From: Jonas Hahnfeld <Hahnfeld@itc.rwth-aachen.de>
Date: Fri, 17 Feb 2017 18:32:51 +0000 (+0000)
Subject: [OpenMP] Remove barriers at cancel and cancellation point
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=696f45e1309f4314286f8835ff6c50c548771bf4;p=clang

[OpenMP] Remove barriers at cancel and cancellation point

This resolves a deadlock with the cancel directive when there is no explicit
cancellation point. In that case, the implicit barrier acts as cancellation
point. After removing the barrier after cancel, the now unmatched barrier for
the explicit cancellation point has to go as well.

This has probably worked before rL255992: With the calls for the explicit
barrier, it was sure that all threads passed a barrier before exiting.

Reported by Simon Convent and Joachim Protze!

Differential Revision: https://reviews.llvm.org/D30088

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@295473 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CGOpenMPRuntime.cpp b/lib/CodeGen/CGOpenMPRuntime.cpp
index e507b39e40..099fa5905b 100644
--- a/lib/CodeGen/CGOpenMPRuntime.cpp
+++ b/lib/CodeGen/CGOpenMPRuntime.cpp
@@ -4724,7 +4724,6 @@ void CGOpenMPRuntime::emitCancellationPointCall(
       auto *Result = CGF.EmitRuntimeCall(
           createRuntimeFunction(OMPRTL__kmpc_cancellationpoint), Args);
       // if (__kmpc_cancellationpoint()) {
-      //  __kmpc_cancel_barrier();
       //   exit from construct;
       // }
       auto *ExitBB = CGF.createBasicBlock(".cancel.exit");
@@ -4732,8 +4731,6 @@ void CGOpenMPRuntime::emitCancellationPointCall(
       auto *Cmp = CGF.Builder.CreateIsNotNull(Result);
       CGF.Builder.CreateCondBr(Cmp, ExitBB, ContBB);
       CGF.EmitBlock(ExitBB);
-      // __kmpc_cancel_barrier();
-      emitBarrierCall(CGF, Loc, OMPD_unknown, /*EmitChecks=*/false);
       // exit from construct;
       auto CancelDest =
           CGF.getOMPCancelDestination(OMPRegionInfo->getDirectiveKind());
@@ -4762,7 +4759,6 @@ void CGOpenMPRuntime::emitCancelCall(CodeGenFunction &CGF, SourceLocation Loc,
       auto *Result = CGF.EmitRuntimeCall(
           RT.createRuntimeFunction(OMPRTL__kmpc_cancel), Args);
       // if (__kmpc_cancel()) {
-      //  __kmpc_cancel_barrier();
       //   exit from construct;
       // }
       auto *ExitBB = CGF.createBasicBlock(".cancel.exit");
@@ -4770,8 +4766,6 @@ void CGOpenMPRuntime::emitCancelCall(CodeGenFunction &CGF, SourceLocation Loc,
       auto *Cmp = CGF.Builder.CreateIsNotNull(Result);
       CGF.Builder.CreateCondBr(Cmp, ExitBB, ContBB);
       CGF.EmitBlock(ExitBB);
-      // __kmpc_cancel_barrier();
-      RT.emitBarrierCall(CGF, Loc, OMPD_unknown, /*EmitChecks=*/false);
       // exit from construct;
       auto CancelDest =
           CGF.getOMPCancelDestination(OMPRegionInfo->getDirectiveKind());
diff --git a/test/OpenMP/cancel_codegen.cpp b/test/OpenMP/cancel_codegen.cpp
index 69acb3d490..2ff9dcc186 100644
--- a/test/OpenMP/cancel_codegen.cpp
+++ b/test/OpenMP/cancel_codegen.cpp
@@ -12,6 +12,8 @@ int main (int argc, char **argv) {
 {
 #pragma omp cancel parallel if(flag)
   argv[0][0] = argc;
+#pragma omp barrier
+  argv[0][0] += argc;
 }
 // CHECK: call void (%ident_t*, i32, void (i32*, i32*, ...)*, ...) @__kmpc_fork_call(
 #pragma omp sections
@@ -20,7 +22,6 @@ int main (int argc, char **argv) {
 }
 // CHECK: call void @__kmpc_for_static_init_4(
 // CHECK: call i32 @__kmpc_cancel(
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: call void @__kmpc_for_static_fini(
 // CHECK: call void @__kmpc_barrier(%ident_t*
 #pragma omp sections
@@ -36,7 +37,6 @@ int main (int argc, char **argv) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
@@ -44,7 +44,6 @@ int main (int argc, char **argv) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
@@ -62,7 +61,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
@@ -109,9 +107,10 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,]+]],
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label %[[RETURN:.+]]
 // CHECK: [[ELSE]]
+// The barrier directive should now call __kmpc_cancel_barrier
+// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[RETURN]]
 // CHECK: ret void
@@ -121,7 +120,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,]+]],
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label %[[RETURN:.+]]
 // CHECK: [[RETURN]]
 // CHECK: ret i32 0
@@ -129,7 +127,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: define internal void @{{[^(]+}}(i32* {{[^,]+}}, i32* {{[^,]+}})
 // CHECK: call void @__kmpc_for_static_init_4(
 // CHECK: call i32 @__kmpc_cancel(
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: call void @__kmpc_for_static_fini(
 // CHECK: ret void
 
@@ -139,7 +136,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
@@ -147,7 +143,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
@@ -160,7 +155,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
diff --git a/test/OpenMP/cancellation_point_codegen.cpp b/test/OpenMP/cancellation_point_codegen.cpp
index c87d4015ef..22969141af 100644
--- a/test/OpenMP/cancellation_point_codegen.cpp
+++ b/test/OpenMP/cancellation_point_codegen.cpp
@@ -26,7 +26,6 @@ int main (int argc, char **argv) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
@@ -46,7 +45,6 @@ int main (int argc, char **argv) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
@@ -54,7 +52,6 @@ int main (int argc, char **argv) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
@@ -69,7 +66,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
@@ -116,7 +112,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,]+]],
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label %[[RETURN:.+]]
 // CHECK: [[RETURN]]
 // CHECK: ret void
@@ -126,7 +121,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,]+]],
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label %[[RETURN:.+]]
 // CHECK: [[RETURN]]
 // CHECK: ret i32 0
@@ -137,7 +131,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
@@ -150,7 +143,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
@@ -158,7 +150,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label
@@ -171,7 +162,6 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CMP:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK: br i1 [[CMP]], label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
 // CHECK: [[EXIT]]
-// CHECK: call i32 @__kmpc_cancel_barrier(%ident_t*
 // CHECK: br label
 // CHECK: [[CONTINUE]]
 // CHECK: br label