[gcc/devel/omp/gcc-11] amdgcn: Add waitcnt after LDS write instructions

[gcc/devel/omp/gcc-11] amdgcn: Add waitcnt after LDS write instructions

[Kwok Yeung]

https://gcc.gnu.org/g:3a6d6eaee7fb0c01a77218c5644ea5e91812e8a0

commit 3a6d6eaee7fb0c01a77218c5644ea5e91812e8a0
Author: Julian Brown <julian@codesourcery.com>
Date:   Mon Feb 10 12:26:57 2020 -0800

    amdgcn: Add waitcnt after LDS write instructions
    
    Data-share write (ds_write) instructions do not necessarily complete
    the write to LDS immediately. When a write completes, LGKM_CNT is
    decremented. For now, we wait until LGKM_CNT reaches zero after each
    ds_write instruction.
    
    This fixes a race condition in the case where LDS is read immediately
    after being written. This can happen with broadcast operations.
    
    2020-07-15  Julian Brown  <julian@codesourcery.com>
    
    gcc/
            * config/gcn/gcn-valu.md (scatter<mode>_insn_1offset_ds<exec_scatter>):
            Add waitcnt.
            (*mov<mode>_insn, *movti_insn): Add waitcnt to ds_write alternatives.

Diff:
---
 gcc/ChangeLog.omp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/gcc/ChangeLog.omp b/gcc/ChangeLog.omp
index 4f680f0ddd2..882a2fbf473 100644
--- a/gcc/ChangeLog.omp
+++ b/gcc/ChangeLog.omp
@@ -1,3 +1,9 @@
+2020-07-15  Julian Brown  <julian@codesourcery.com>
+
+	* config/gcn/gcn-valu.md (scatter<mode>_insn_1offset_ds<exec_scatter>):
+	Add waitcnt.
+	(*mov<mode>_insn, *movti_insn): Add waitcnt to ds_write alternatives.
+
 2020-07-15  Julian Brown  <julian@codesourcery.com>
 
 	* config/gcn/gcn-protos.h (gcn_goacc_adjust_private_decl): Update