Hi, For sm_7x atomic stores we fall back on expand_atomic_store, but this results in using membar.sys for shared stores.
Fix this by adding an nvptx_atomic_store insn that adds a membar.cta for a shared store. Tested on x86_64 with nvptx accelerator. Committed to trunk. Thanks, - Tom [nvptx] Handle sm_7x shared atomic store more optimal gcc/ChangeLog: 2022-02-02 Tom de Vries <tdevr...@suse.de> * config/nvptx/nvptx.md (define_insn "nvptx_atomic_store<mode>"): New define_insn. (define_expand "atomic_store<mode>"): Use nvptx_atomic_store<mode> for TARGET_SM70. (define_c_enum "unspecv"): Add UNSPECV_ST. gcc/testsuite/ChangeLog: 2022-02-02 Tom de Vries <tdevr...@suse.de> * gcc.target/nvptx/atomic-store-2.c: New test. --- gcc/config/nvptx/nvptx.md | 22 +++++++++++++++++++-- gcc/testsuite/gcc.target/nvptx/atomic-store-2.c | 26 +++++++++++++++++++++++++ 2 files changed, 46 insertions(+), 2 deletions(-) diff --git a/gcc/config/nvptx/nvptx.md b/gcc/config/nvptx/nvptx.md index 1a283b41922..4c378ec6ecb 100644 --- a/gcc/config/nvptx/nvptx.md +++ b/gcc/config/nvptx/nvptx.md @@ -57,6 +57,7 @@ (define_c_enum "unspecv" [ UNSPECV_CAS UNSPECV_CAS_LOCAL UNSPECV_XCHG + UNSPECV_ST UNSPECV_BARSYNC UNSPECV_WARPSYNC UNSPECV_UNIFORM_WARP_CHECK @@ -2067,8 +2068,11 @@ (define_expand "atomic_store<mode>" } if (TARGET_SM70) - /* Fall back to expand_atomic_store. */ - FAIL; + { + emit_insn (gen_nvptx_atomic_store<mode> (operands[0], operands[1], + operands[2])); + DONE; + } bool maybe_shared_p = nvptx_mem_maybe_shared_p (operands[0]); if (!maybe_shared_p) @@ -2081,6 +2085,20 @@ (define_expand "atomic_store<mode>" DONE; }) +(define_insn "nvptx_atomic_store<mode>" + [(set (match_operand:SDIM 0 "memory_operand" "+m") ;; memory + (unspec_volatile:SDIM + [(match_operand:SDIM 1 "nvptx_nonmemory_operand" "Ri") ;; input + (match_operand:SI 2 "const_int_operand")] ;; model + UNSPECV_ST))] + "TARGET_SM70" + { + const char *t + = "%.\tst%A0.b%T0\t%0, %1;"; + return nvptx_output_atomic_insn (t, operands, 0, 2); + } + [(set_attr "atomic" "true")]) + (define_insn "atomic_fetch_add<mode>" [(set (match_operand:SDIM 1 "memory_operand" "+m") (unspec_volatile:SDIM diff --git a/gcc/testsuite/gcc.target/nvptx/atomic-store-2.c b/gcc/testsuite/gcc.target/nvptx/atomic-store-2.c new file mode 100644 index 00000000000..cd5e4c38267 --- /dev/null +++ b/gcc/testsuite/gcc.target/nvptx/atomic-store-2.c @@ -0,0 +1,26 @@ +/* Test the atomic store expansion for sm > sm_6x targets, + shared state space. */ + +/* { dg-do compile } */ +/* { dg-options "-misa=sm_75" } */ + +enum memmodel +{ + MEMMODEL_SEQ_CST = 5 +}; + +unsigned int u32 __attribute__((shared)); +unsigned long long int u64 __attribute__((shared)); + +int +main() +{ + __atomic_store_n (&u32, 0, MEMMODEL_SEQ_CST); + __atomic_store_n (&u64, 0, MEMMODEL_SEQ_CST); + + return 0; +} + +/* { dg-final { scan-assembler-times "st.shared.b32" 1 } } */ +/* { dg-final { scan-assembler-times "st.shared.b64" 1 } } */ +/* { dg-final { scan-assembler-times "membar.cta" 4 } } */