[OPENMP] Fix use of unsigned counters in loops with zero trip count.

Patch fixes bugs in codegen for loops with unsigned counters and zero trip count. Previously preconditions for all loops were built using logic (Upper - Lower) > 0. But if the loop is a loop with zero trip count, then Upper - Lower is < 0 only for signed integer, for unsigned we're running into an underflow situation.
In this patch we're using original Lower<Upper condition to check that loop body can be executed at least once. Also this allows to skip code generation for loops, if it is known that preconditions for the loop are always false.
Differential Revision: http://reviews.llvm.org/D9103

llvm-svn: 235500

1 files changed, 0 insertions, 22 deletions

diff --git a/clang/test/OpenMP/parallel_for_codegen.cpp b/clang/test/OpenMP/parallel_for_codegen.cpp
index 63ae11bea53..3942fad9328 100644
--- a/clang/test/OpenMP/parallel_for_codegen.cpp
+++ b/clang/test/OpenMP/parallel_for_codegen.cpp
@@ -47,11 +47,7 @@ void without_schedule_clause(float *a, float *b, float *c, float *d) {
 // CHECK-NEXT: br label %{{.+}}
   }
 // CHECK: [[LOOP1_END]]
-// CHECK: [[GTID_REF:%.+]] = load i32*, i32** [[GTID_REF_ADDR]],
-// CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: call void @__kmpc_for_static_fini([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]])
-// CHECK: [[GTID_REF:%.+]] = load i32*, i32** [[GTID_REF_ADDR]],
-// CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: call {{.+}} @__kmpc_cancel_barrier([[IDENT_T_TY]]* [[DEFAULT_LOC_BARRIER:[@%].+]], i32 [[GTID]])
 // CHECK: ret void
 }
@@ -95,11 +91,7 @@ void static_not_chunked(float *a, float *b, float *c, float *d) {
 // CHECK-NEXT: br label %{{.+}}
   }
 // CHECK: [[LOOP1_END]]
-// CHECK: [[GTID_REF:%.+]] = load i32*, i32** [[GTID_REF_ADDR]],
-// CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: call void @__kmpc_for_static_fini([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]])
-// CHECK: [[GTID_REF:%.+]] = load i32*, i32** [[GTID_REF_ADDR]],
-// CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: call {{.+}} @__kmpc_cancel_barrier([[IDENT_T_TY]]* [[DEFAULT_LOC_BARRIER:[@%].+]], i32 [[GTID]])
 // CHECK: ret void
 }
@@ -162,11 +154,7 @@ void static_chunked(float *a, float *b, float *c, float *d) {
 // CHECK-NEXT: store i32 [[ADD_UB]], i32* [[OMP_UB]]
 
 // CHECK: [[O_LOOP1_END]]
-// CHECK: [[GTID_REF:%.+]] = load i32*, i32** [[GTID_REF_ADDR]],
-// CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: call void @__kmpc_for_static_fini([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]])
-// CHECK: [[GTID_REF:%.+]] = load i32*, i32** [[GTID_REF_ADDR]],
-// CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: call {{.+}} @__kmpc_cancel_barrier([[IDENT_T_TY]]* [[DEFAULT_LOC_BARRIER:[@%].+]], i32 [[GTID]])
 // CHECK: ret void
 }
@@ -181,8 +169,6 @@ void dynamic1(float *a, float *b, float *c, float *d) {
 // CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: call void @__kmpc_dispatch_init_8u([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]], i32 35, i64 0, i64 16908287, i64 1, i64 1)
 //
-// CHECK: [[GTID_REF:%.+]] = load i32*, i32** [[GTID_REF_ADDR]],
-// CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: [[HASWORK:%.+]] = call i32 @__kmpc_dispatch_next_8u([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]], i32* [[OMP_ISLAST:%[^,]+]], i64* [[OMP_LB:%[^,]+]], i64* [[OMP_UB:%[^,]+]], i64* [[OMP_ST:%[^,]+]])
 // CHECK-NEXT: [[O_CMP:%.+]] = icmp ne i32 [[HASWORK]], 0
 // CHECK-NEXT: br i1 [[O_CMP]], label %[[O_LOOP1_BODY:[^,]+]], label %[[O_LOOP1_END:[^,]+]]
@@ -214,8 +200,6 @@ void dynamic1(float *a, float *b, float *c, float *d) {
   }
 // CHECK: [[LOOP1_END]]
 // CHECK: [[O_LOOP1_END]]
-// CHECK: [[GTID_REF:%.+]] = load i32*, i32** [[GTID_REF_ADDR]],
-// CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: call {{.+}} @__kmpc_cancel_barrier([[IDENT_T_TY]]* [[DEFAULT_LOC_BARRIER:[@%].+]], i32 [[GTID]])
 // CHECK: ret void
 }
@@ -230,8 +214,6 @@ void guided7(float *a, float *b, float *c, float *d) {
 // CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: call void @__kmpc_dispatch_init_8u([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]], i32 36, i64 0, i64 16908287, i64 1, i64 7)
 //
-// CHECK: [[GTID_REF:%.+]] = load i32*, i32** [[GTID_REF_ADDR]],
-// CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: [[HASWORK:%.+]] = call i32 @__kmpc_dispatch_next_8u([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]], i32* [[OMP_ISLAST:%[^,]+]], i64* [[OMP_LB:%[^,]+]], i64* [[OMP_UB:%[^,]+]], i64* [[OMP_ST:%[^,]+]])
 // CHECK-NEXT: [[O_CMP:%.+]] = icmp ne i32 [[HASWORK]], 0
 // CHECK-NEXT: br i1 [[O_CMP]], label %[[O_LOOP1_BODY:[^,]+]], label %[[O_LOOP1_END:[^,]+]]
@@ -263,8 +245,6 @@ void guided7(float *a, float *b, float *c, float *d) {
   }
 // CHECK: [[LOOP1_END]]
 // CHECK: [[O_LOOP1_END]]
-// CHECK: [[GTID_REF:%.+]] = load i32*, i32** [[GTID_REF_ADDR]],
-// CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: call {{.+}} @__kmpc_cancel_barrier([[IDENT_T_TY]]* [[DEFAULT_LOC_BARRIER:[@%].+]], i32 [[GTID]])
 // CHECK: ret void
 }
@@ -332,8 +312,6 @@ void runtime(float *a, float *b, float *c, float *d) {
 // CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: call void @__kmpc_dispatch_init_4([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]], i32 37, i32 0, i32 199, i32 1, i32 1)
 //
-// CHECK: [[GTID_REF:%.+]] = load i32*, i32** [[GTID_REF_ADDR]],
-// CHECK: [[GTID:%.+]] = load i32, i32* [[GTID_REF]],
 // CHECK: [[HASWORK:%.+]] = call i32 @__kmpc_dispatch_next_4([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]], i32* [[OMP_ISLAST:%[^,]+]], i32* [[OMP_LB:%[^,]+]], i32* [[OMP_UB:%[^,]+]], i32* [[OMP_ST:%[^,]+]])
 // CHECK-NEXT: [[O_CMP:%.+]] = icmp ne i32 [[HASWORK]], 0
 // CHECK-NEXT: br i1 [[O_CMP]], label %[[O_LOOP1_BODY:[^,]+]], label %[[O_LOOP1_END:[^,]+]]