[llvm] r286530 - Revert "[AMDGPU] Allow hoisting of comparisons out of a loop and eliminate condition copies"

Stanislav Mekhanoshin via llvm-commits llvm-commits at lists.llvm.org
Thu Nov 10 16:22:35 PST 2016


Author: rampitec
Date: Thu Nov 10 18:22:34 2016
New Revision: 286530

URL: http://llvm.org/viewvc/llvm-project?rev=286530&view=rev
Log:
Revert "[AMDGPU] Allow hoisting of comparisons out of a loop and eliminate condition copies"

This reverts commit r286171, it breaks piglit test fs-discard-exit-2

Removed:
    llvm/trunk/test/CodeGen/AMDGPU/host-cond.ll
Modified:
    llvm/trunk/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
    llvm/trunk/lib/Target/AMDGPU/SILowerI1Copies.cpp
    llvm/trunk/test/CodeGen/AMDGPU/branch-relaxation.ll

Modified: llvm/trunk/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AMDGPU/AMDGPUISelLowering.cpp?rev=286530&r1=286529&r2=286530&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AMDGPU/AMDGPUISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/AMDGPU/AMDGPUISelLowering.cpp Thu Nov 10 18:22:34 2016
@@ -440,7 +440,6 @@ AMDGPUTargetLowering::AMDGPUTargetLoweri
 
   setSchedulingPreference(Sched::RegPressure);
   setJumpIsExpensive(true);
-  setHasMultipleConditionRegisters(true);
 
   // SI at least has hardware support for floating point exceptions, but no way
   // of using or handling them is implemented. They are also optional in OpenCL

Modified: llvm/trunk/lib/Target/AMDGPU/SILowerI1Copies.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AMDGPU/SILowerI1Copies.cpp?rev=286530&r1=286529&r2=286530&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AMDGPU/SILowerI1Copies.cpp (original)
+++ llvm/trunk/lib/Target/AMDGPU/SILowerI1Copies.cpp Thu Nov 10 18:22:34 2016
@@ -121,31 +121,11 @@ bool SILowerI1Copies::runOnMachineFuncti
           }
         }
 
-        // If there are uses which are just a copy back from this new VReg_1
-        // to another SGPR_64 just forward propagate original SGPR_64.
-        SmallVector<MachineInstr *, 4> RegUses;
-        for (auto &Use : MRI.use_instructions(Dst.getReg()))
-          if (Use.isFullCopy())
-            RegUses.push_back(&Use);
-
-        while (!RegUses.empty()) {
-          MachineInstr *Use = RegUses.pop_back_val();
-          if (Use->getOperand(1).getReg() == Dst.getReg()) {
-            unsigned RegCopy = Use->getOperand(0).getReg();
-            if (!TargetRegisterInfo::isVirtualRegister(RegCopy))
-              continue;
-            Use->eraseFromParent();
-            MRI.replaceRegWith(RegCopy, Src.getReg());
-          }
-        }
-
-        if (!MRI.use_empty(Dst.getReg()))
-          BuildMI(MBB, &MI, DL, TII->get(AMDGPU::V_CNDMASK_B32_e64))
-            .addOperand(Dst)
-            .addImm(0)
-            .addImm(-1)
-            .addOperand(Src);
-
+        BuildMI(MBB, &MI, DL, TII->get(AMDGPU::V_CNDMASK_B32_e64))
+          .addOperand(Dst)
+          .addImm(0)
+          .addImm(-1)
+          .addOperand(Src);
         MI.eraseFromParent();
       } else if (TRI->getCommonSubClass(DstRC, &AMDGPU::SGPR_64RegClass) &&
                  SrcRC == &AMDGPU::VReg_1RegClass) {

Modified: llvm/trunk/test/CodeGen/AMDGPU/branch-relaxation.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AMDGPU/branch-relaxation.ll?rev=286530&r1=286529&r2=286530&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AMDGPU/branch-relaxation.ll (original)
+++ llvm/trunk/test/CodeGen/AMDGPU/branch-relaxation.ll Thu Nov 10 18:22:34 2016
@@ -90,7 +90,7 @@ bb3:
 ; GCN-LABEL: {{^}}uniform_conditional_min_long_forward_vcnd_branch:
 ; GCN: s_load_dword [[CND:s[0-9]+]]
 ; GCN-DAG: v_mov_b32_e32 [[V_CND:v[0-9]+]], [[CND]]
-; GCN-DAG: v_cmp_eq_f32_e64 {{vcc|(s\[[0-9]+:[0-9]+\])}}, [[CND]], 0
+; GCN-DAG: v_cmp_eq_f32_e64 vcc, [[CND]], 0
 ; GCN: s_cbranch_vccz [[LONGBB:BB[0-9]+_[0-9]+]]
 
 ; GCN-NEXT: [[LONG_JUMP:BB[0-9]+_[0-9]+]]: ; %bb0
@@ -492,8 +492,8 @@ ret:
 ; GCN: s_setpc_b64
 
 ; GCN: [[LONG_BR_DEST0]]
-; GCN: v_cmp_ne_u32_e32
-; GCN-NEXT: s_cbranch_vccz
+; GCN: s_cmp_eq_u32
+; GCN-NEXT: s_cbranch_scc0
 ; GCN: s_setpc_b64
 
 ; GCN: s_endpgm

Removed: llvm/trunk/test/CodeGen/AMDGPU/host-cond.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AMDGPU/host-cond.ll?rev=286529&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/AMDGPU/host-cond.ll (original)
+++ llvm/trunk/test/CodeGen/AMDGPU/host-cond.ll (removed)
@@ -1,46 +0,0 @@
-; RUN: llc -march=amdgcn -verify-machineinstrs < %s | FileCheck %s
-
-; Check that invariant compare is hoisted out of the loop.
-; At the same time condition shall not be serialized into a VGPR and deserialized later
-; using another v_cmp + v_cndmask, but used directly in s_and_saveexec_b64.
-
-; CHECK: v_cmp_{{..}}_u32_e64 [[COND:s\[[0-9]+:[0-9]+\]]]
-; CHECK: BB0_1:
-; CHECK-NOT: v_cmp
-; CHECK_NOT: v_cndmask
-; CHECK: s_and_saveexec_b64 s[{{[[0-9]+:[0-9]+}}], [[COND]]
-; CHECK: BB0_2:
-
-define amdgpu_kernel void @hoist_cond(float addrspace(1)* nocapture %arg, float addrspace(1)* noalias nocapture readonly %arg1, i32 %arg3, i32 %arg4) {
-bb:
-  %tmp = tail call i32 @llvm.amdgcn.workitem.id.x() #0
-  %tmp5 = icmp ult i32 %tmp, %arg3
-  br label %bb1
-
-bb1:                                              ; preds = %bb3, %bb
-  %tmp7 = phi i32 [ %arg4, %bb ], [ %tmp16, %bb3 ]
-  %tmp8 = phi float [ 0.000000e+00, %bb ], [ %tmp15, %bb3 ]
-  br i1 %tmp5, label %bb2, label %bb3
-
-bb2:                                              ; preds = %bb1
-  %tmp10 = zext i32 %tmp7 to i64
-  %tmp11 = getelementptr inbounds float, float addrspace(1)* %arg1, i64 %tmp10
-  %tmp12 = load float, float addrspace(1)* %tmp11, align 4
-  br label %bb3
-
-bb3:                                             ; preds = %bb2, %bb1
-  %tmp14 = phi float [ %tmp12, %bb2 ], [ 0.000000e+00, %bb1 ]
-  %tmp15 = fadd float %tmp8, %tmp14
-  %tmp16 = add i32 %tmp7, -1
-  %tmp17 = icmp eq i32 %tmp16, 0
-  br i1 %tmp17, label %bb4, label %bb1
-
-bb4:                                             ; preds = %bb3
-  store float %tmp15, float addrspace(1)* %arg, align 4
-  ret void
-}
-
-; Function Attrs: nounwind readnone
-declare i32 @llvm.amdgcn.workitem.id.x() #0
-
-attributes #0 = { nounwind readnone }




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