From: Konstantin Zhuravlyov <kzhuravl_dev@outlook.com>
Date: Fri, 30 Sep 2016 16:50:36 +0000 (+0000)
Subject: [AMDGPU] Ask subtarget if waitcnt instruction is needed before barrier instruction
X-Git-Tag: llvmorg-4.0.0-rc1~8480
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d7bdf24f32b7f7b7fe81ff38b51d94478a6e3e87;p=platform%2Fupstream%2Fllvm.git

[AMDGPU] Ask subtarget if waitcnt instruction is needed before barrier instruction

Differential Revision: https://reviews.llvm.org/D24985

llvm-svn: 282875
---

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h b/llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h
index c278cc5..3298a4b 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h
+++ b/llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h
@@ -540,6 +540,12 @@ public:
 
   /// Return the maximum number of waves per SIMD for kernels using \p VGPRs VGPRs
   unsigned getOccupancyWithNumVGPRs(unsigned VGPRs) const;
+
+  /// \returns True if waitcnt instruction is needed before barrier instruction,
+  /// false otherwise.
+  bool needWaitcntBeforeBarrier() const {
+    return true;
+  }
 };
 
 } // End namespace llvm
diff --git a/llvm/lib/Target/AMDGPU/SIInsertWaits.cpp b/llvm/lib/Target/AMDGPU/SIInsertWaits.cpp
index d24588d..b9551be 100644
--- a/llvm/lib/Target/AMDGPU/SIInsertWaits.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInsertWaits.cpp
@@ -590,8 +590,9 @@ bool SIInsertWaits::runOnMachineFunction(MachineFunction &MF) {
       // S_SENDMSG implicitly waits for all outstanding LGKM transfers to finish,
       // but we also want to wait for any other outstanding transfers before
       // signalling other hardware blocks
-      if (I->getOpcode() == AMDGPU::S_BARRIER ||
-          I->getOpcode() == AMDGPU::S_SENDMSG)
+      if ((I->getOpcode() == AMDGPU::S_BARRIER &&
+               ST->needWaitcntBeforeBarrier()) ||
+           I->getOpcode() == AMDGPU::S_SENDMSG)
         Required = LastIssued;
       else
         Required = handleOperands(*I);