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Differential D67573

Fix __atomic_is_lock_free's return type.
Needs ReviewPublic

Authored by jyknight on Sep 13 2019, 3:01 PM.

Details

Reviewers
rsmith
Summary

It is specified to return a bool in GCC's documentation and
implementation, but the clang builtin says it returns an int. This
would be pretty much harmless, if it was just the builtin.

However, when clang translates the builtin into a libcall, it _also_
generates the libcall with an int return type, while the actual
library function in libatomic returns a bool.

This mismatch in return types results in an actual ABI mismatch and
thus incorrect results (interpreting false return value as true) on at
least x86_64.

Diff Detail

Event Timeline

jyknight created this revision.Sep 13 2019, 3:01 PM
Herald added a project: Restricted Project. · View Herald TranscriptSep 13 2019, 3:01 PM
Herald added subscribers: cfe-commits, jfb, kristof.beyls. · View Herald Transcript
Harbormaster completed remote builds in B38121: Diff 220178.Sep 13 2019, 3:01 PM
jyknight added a comment.Sep 24 2019, 2:17 PM

Ping.

jyknight added a comment.Nov 11 2019, 8:11 AM

Ping!

Revision Contents

PathSize
clang/
include/
clang/
Basic/
4 lines
test/
CodeGen/
10 lines
10 lines

Diff 220178

clang/include/clang/Basic/Builtins.def

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ATOMIC_BUILTIN(__c11_atomic_compare_exchange_weak, "v.", "t") ATOMIC_BUILTIN(__c11_atomic_compare_exchange_weak, "v.", "t")
ATOMIC_BUILTIN(__c11_atomic_fetch_add, "v.", "t") ATOMIC_BUILTIN(__c11_atomic_fetch_add, "v.", "t")
ATOMIC_BUILTIN(__c11_atomic_fetch_sub, "v.", "t") ATOMIC_BUILTIN(__c11_atomic_fetch_sub, "v.", "t")
ATOMIC_BUILTIN(__c11_atomic_fetch_and, "v.", "t") ATOMIC_BUILTIN(__c11_atomic_fetch_and, "v.", "t")
ATOMIC_BUILTIN(__c11_atomic_fetch_or, "v.", "t") ATOMIC_BUILTIN(__c11_atomic_fetch_or, "v.", "t")
ATOMIC_BUILTIN(__c11_atomic_fetch_xor, "v.", "t") ATOMIC_BUILTIN(__c11_atomic_fetch_xor, "v.", "t")
BUILTIN(__c11_atomic_thread_fence, "vi", "n") BUILTIN(__c11_atomic_thread_fence, "vi", "n")
BUILTIN(__c11_atomic_signal_fence, "vi", "n") BUILTIN(__c11_atomic_signal_fence, "vi", "n")
BUILTIN(__c11_atomic_is_lock_free, "iz", "n") BUILTIN(__c11_atomic_is_lock_free, "bz", "n")
// GNU atomic builtins. // GNU atomic builtins.
ATOMIC_BUILTIN(__atomic_load, "v.", "t") ATOMIC_BUILTIN(__atomic_load, "v.", "t")
ATOMIC_BUILTIN(__atomic_load_n, "v.", "t") ATOMIC_BUILTIN(__atomic_load_n, "v.", "t")
ATOMIC_BUILTIN(__atomic_store, "v.", "t") ATOMIC_BUILTIN(__atomic_store, "v.", "t")
ATOMIC_BUILTIN(__atomic_store_n, "v.", "t") ATOMIC_BUILTIN(__atomic_store_n, "v.", "t")
ATOMIC_BUILTIN(__atomic_exchange, "v.", "t") ATOMIC_BUILTIN(__atomic_exchange, "v.", "t")
ATOMIC_BUILTIN(__atomic_exchange_n, "v.", "t") ATOMIC_BUILTIN(__atomic_exchange_n, "v.", "t")
Show All 11 Lines
ATOMIC_BUILTIN(__atomic_or_fetch, "v.", "t") ATOMIC_BUILTIN(__atomic_or_fetch, "v.", "t")
ATOMIC_BUILTIN(__atomic_xor_fetch, "v.", "t") ATOMIC_BUILTIN(__atomic_xor_fetch, "v.", "t")
ATOMIC_BUILTIN(__atomic_nand_fetch, "v.", "t") ATOMIC_BUILTIN(__atomic_nand_fetch, "v.", "t")
BUILTIN(__atomic_test_and_set, "bvD*i", "n") BUILTIN(__atomic_test_and_set, "bvD*i", "n")
BUILTIN(__atomic_clear, "vvD*i", "n") BUILTIN(__atomic_clear, "vvD*i", "n")
BUILTIN(__atomic_thread_fence, "vi", "n") BUILTIN(__atomic_thread_fence, "vi", "n")
BUILTIN(__atomic_signal_fence, "vi", "n") BUILTIN(__atomic_signal_fence, "vi", "n")
BUILTIN(__atomic_always_lock_free, "izvCD*", "n") BUILTIN(__atomic_always_lock_free, "izvCD*", "n")
BUILTIN(__atomic_is_lock_free, "izvCD*", "n") BUILTIN(__atomic_is_lock_free, "bzvCD*", "n")
// OpenCL 2.0 atomic builtins. // OpenCL 2.0 atomic builtins.
ATOMIC_BUILTIN(__opencl_atomic_init, "v.", "t") ATOMIC_BUILTIN(__opencl_atomic_init, "v.", "t")
ATOMIC_BUILTIN(__opencl_atomic_load, "v.", "t") ATOMIC_BUILTIN(__opencl_atomic_load, "v.", "t")
ATOMIC_BUILTIN(__opencl_atomic_store, "v.", "t") ATOMIC_BUILTIN(__opencl_atomic_store, "v.", "t")
ATOMIC_BUILTIN(__opencl_atomic_exchange, "v.", "t") ATOMIC_BUILTIN(__opencl_atomic_exchange, "v.", "t")
ATOMIC_BUILTIN(__opencl_atomic_compare_exchange_strong, "v.", "t") ATOMIC_BUILTIN(__opencl_atomic_compare_exchange_strong, "v.", "t")
ATOMIC_BUILTIN(__opencl_atomic_compare_exchange_weak, "v.", "t") ATOMIC_BUILTIN(__opencl_atomic_compare_exchange_weak, "v.", "t")
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clang/test/CodeGen/atomic-ops.c

Show First 20 Lines • Show All 337 Lines • ▼ Show 20 Linesstruct Seventeen {
char c[17]; char c[17];
} seventeen; } seventeen;
struct Incomplete; struct Incomplete;
int lock_free(struct Incomplete *incomplete) { int lock_free(struct Incomplete *incomplete) {
// CHECK-LABEL: @lock_free // CHECK-LABEL: @lock_free
// CHECK: call i32 @__atomic_is_lock_free(i32 3, i8* null) // CHECK: call zeroext i1 @__atomic_is_lock_free(i32 3, i8* null)
__c11_atomic_is_lock_free(3); __c11_atomic_is_lock_free(3);
// CHECK: call i32 @__atomic_is_lock_free(i32 16, i8* {{.*}}@sixteen{{.*}}) // CHECK: call zeroext i1 @__atomic_is_lock_free(i32 16, i8* {{.*}}@sixteen{{.*}})
__atomic_is_lock_free(16, &sixteen); __atomic_is_lock_free(16, &sixteen);
// CHECK: call i32 @__atomic_is_lock_free(i32 17, i8* {{.*}}@seventeen{{.*}}) // CHECK: call zeroext i1 @__atomic_is_lock_free(i32 17, i8* {{.*}}@seventeen{{.*}})
__atomic_is_lock_free(17, &seventeen); __atomic_is_lock_free(17, &seventeen);
// CHECK: call i32 @__atomic_is_lock_free(i32 4, {{.*}}) // CHECK: call zeroext i1 @__atomic_is_lock_free(i32 4, {{.*}})
__atomic_is_lock_free(4, incomplete); __atomic_is_lock_free(4, incomplete);
char cs[20]; char cs[20];
// CHECK: call i32 @__atomic_is_lock_free(i32 4, {{.*}}) // CHECK: call zeroext i1 @__atomic_is_lock_free(i32 4, {{.*}})
__atomic_is_lock_free(4, cs+1); __atomic_is_lock_free(4, cs+1);
// CHECK-NOT: call // CHECK-NOT: call
__atomic_always_lock_free(3, 0); __atomic_always_lock_free(3, 0);
__atomic_always_lock_free(16, 0); __atomic_always_lock_free(16, 0);
__atomic_always_lock_free(17, 0); __atomic_always_lock_free(17, 0);
__atomic_always_lock_free(16, &sixteen); __atomic_always_lock_free(16, &sixteen);
__atomic_always_lock_free(17, &seventeen); __atomic_always_lock_free(17, &seventeen);
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clang/test/CodeGen/big-atomic-ops.c

Show First 20 Lines • Show All 192 Lines • ▼ Show 20 Lines
} sixteen; } sixteen;
struct Seventeen { struct Seventeen {
char c[17]; char c[17];
} seventeen; } seventeen;
int lock_free(struct Incomplete *incomplete) { int lock_free(struct Incomplete *incomplete) {
// CHECK: @lock_free // CHECK: @lock_free
// CHECK: call i32 @__atomic_is_lock_free(i64 3, i8* null) // CHECK: call zeroext i1 @__atomic_is_lock_free(i64 3, i8* null)
__c11_atomic_is_lock_free(3); __c11_atomic_is_lock_free(3);
// CHECK: call i32 @__atomic_is_lock_free(i64 16, i8* {{.*}}@sixteen{{.*}}) // CHECK: call zeroext i1 @__atomic_is_lock_free(i64 16, i8* {{.*}}@sixteen{{.*}})
__atomic_is_lock_free(16, &sixteen); __atomic_is_lock_free(16, &sixteen);
// CHECK: call i32 @__atomic_is_lock_free(i64 17, i8* {{.*}}@seventeen{{.*}}) // CHECK: call zeroext i1 @__atomic_is_lock_free(i64 17, i8* {{.*}}@seventeen{{.*}})
__atomic_is_lock_free(17, &seventeen); __atomic_is_lock_free(17, &seventeen);
// CHECK: call i32 @__atomic_is_lock_free(i64 4, {{.*}}) // CHECK: call zeroext i1 @__atomic_is_lock_free(i64 4, {{.*}})
__atomic_is_lock_free(4, incomplete); __atomic_is_lock_free(4, incomplete);
char cs[20]; char cs[20];
// CHECK: call i32 @__atomic_is_lock_free(i64 4, {{.*}}) // CHECK: call zeroext i1 @__atomic_is_lock_free(i64 4, {{.*}})
__atomic_is_lock_free(4, cs+1); __atomic_is_lock_free(4, cs+1);
// CHECK-NOT: call // CHECK-NOT: call
__atomic_always_lock_free(3, 0); __atomic_always_lock_free(3, 0);
__atomic_always_lock_free(16, 0); __atomic_always_lock_free(16, 0);
__atomic_always_lock_free(17, 0); __atomic_always_lock_free(17, 0);
__atomic_always_lock_free(16, &sixteen); __atomic_always_lock_free(16, &sixteen);
__atomic_always_lock_free(17, &seventeen); __atomic_always_lock_free(17, &seventeen);
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