[llvm] r354271 - [MCA] Correctly update register definitions in the PRF after move elimination.
Andrea Di Biagio via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 18 06:15:26 PST 2019
Author: adibiagio
Date: Mon Feb 18 06:15:25 2019
New Revision: 354271
URL: http://llvm.org/viewvc/llvm-project?rev=354271&view=rev
Log:
[MCA] Correctly update register definitions in the PRF after move elimination.
This patch fixes a bug where register writes performed by optimizable register
moves were sometimes wrongly treated like partial register updates. Before this
patch, llvm-mca wrongly predicted a 1.50 IPC for test reg-move-elimination-6.s
(added by this patch). With this patch, llvm-mca correctly updates the register
defintions in the PRF, and the IPC for that test is now correctly reported as 2.
Added:
llvm/trunk/test/tools/llvm-mca/X86/BtVer2/reg-move-elimination-6.s
Modified:
llvm/trunk/lib/MCA/HardwareUnits/RegisterFile.cpp
Modified: llvm/trunk/lib/MCA/HardwareUnits/RegisterFile.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MCA/HardwareUnits/RegisterFile.cpp?rev=354271&r1=354270&r2=354271&view=diff
==============================================================================
--- llvm/trunk/lib/MCA/HardwareUnits/RegisterFile.cpp (original)
+++ llvm/trunk/lib/MCA/HardwareUnits/RegisterFile.cpp Mon Feb 18 06:15:25 2019
@@ -330,30 +330,25 @@ bool RegisterFile::tryEliminateMove(Writ
if (RMT.AllowZeroMoveEliminationOnly && !IsZeroMove)
return false;
- MCPhysReg FromReg = RS.getRegisterID();
- MCPhysReg ToReg = WS.getRegisterID();
-
// Construct an alias.
- MCPhysReg AliasReg = FromReg;
- if (RRIFrom.RenameAs)
- AliasReg = RRIFrom.RenameAs;
+ MCPhysReg AliasedReg =
+ RRIFrom.RenameAs ? RRIFrom.RenameAs : RS.getRegisterID();
+ MCPhysReg AliasReg = RRITo.RenameAs ? RRITo.RenameAs : WS.getRegisterID();
- const RegisterRenamingInfo &RMAlias = RegisterMappings[AliasReg].second;
+ const RegisterRenamingInfo &RMAlias = RegisterMappings[AliasedReg].second;
if (RMAlias.AliasRegID)
- AliasReg = RMAlias.AliasRegID;
+ AliasedReg = RMAlias.AliasRegID;
- if (AliasReg != ToReg) {
- RegisterMappings[ToReg].second.AliasRegID = AliasReg;
- for (MCSubRegIterator I(ToReg, &MRI); I.isValid(); ++I)
- RegisterMappings[*I].second.AliasRegID = AliasReg;
- }
+ RegisterMappings[AliasReg].second.AliasRegID = AliasedReg;
+ for (MCSubRegIterator I(AliasReg, &MRI); I.isValid(); ++I)
+ RegisterMappings[*I].second.AliasRegID = AliasedReg;
- RMT.NumMoveEliminated++;
if (IsZeroMove) {
WS.setWriteZero();
RS.setReadZero();
}
WS.setEliminated();
+ RMT.NumMoveEliminated++;
return true;
}
Added: llvm/trunk/test/tools/llvm-mca/X86/BtVer2/reg-move-elimination-6.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-mca/X86/BtVer2/reg-move-elimination-6.s?rev=354271&view=auto
==============================================================================
--- llvm/trunk/test/tools/llvm-mca/X86/BtVer2/reg-move-elimination-6.s (added)
+++ llvm/trunk/test/tools/llvm-mca/X86/BtVer2/reg-move-elimination-6.s Mon Feb 18 06:15:25 2019
@@ -0,0 +1,119 @@
+# NOTE: Assertions have been autogenerated by utils/update_mca_test_checks.py
+# RUN: llvm-mca -mtriple=x86_64-unknown-unknown -mcpu=btver2 -timeline -timeline-max-iterations=3 -register-file-stats < %s | FileCheck %s
+
+xor %rsi, %rsi
+add %rcx, %rcx
+add %rcx, %rcx
+add %rcx, %rcx
+add %rcx, %rcx
+mov %esi, %ecx
+
+# CHECK: Iterations: 100
+# CHECK-NEXT: Instructions: 600
+# CHECK-NEXT: Total Cycles: 304
+# CHECK-NEXT: Total uOps: 600
+
+# CHECK: Dispatch Width: 2
+# CHECK-NEXT: uOps Per Cycle: 1.97
+# CHECK-NEXT: IPC: 1.97
+# CHECK-NEXT: Block RThroughput: 3.0
+
+# CHECK: Instruction Info:
+# CHECK-NEXT: [1]: #uOps
+# CHECK-NEXT: [2]: Latency
+# CHECK-NEXT: [3]: RThroughput
+# CHECK-NEXT: [4]: MayLoad
+# CHECK-NEXT: [5]: MayStore
+# CHECK-NEXT: [6]: HasSideEffects (U)
+
+# CHECK: [1] [2] [3] [4] [5] [6] Instructions:
+# CHECK-NEXT: 1 0 0.50 xorq %rsi, %rsi
+# CHECK-NEXT: 1 1 0.50 addq %rcx, %rcx
+# CHECK-NEXT: 1 1 0.50 addq %rcx, %rcx
+# CHECK-NEXT: 1 1 0.50 addq %rcx, %rcx
+# CHECK-NEXT: 1 1 0.50 addq %rcx, %rcx
+# CHECK-NEXT: 1 1 0.50 movl %esi, %ecx
+
+# CHECK: Register File statistics:
+# CHECK-NEXT: Total number of mappings created: 800
+# CHECK-NEXT: Max number of mappings used: 12
+
+# CHECK: * Register File #1 -- JFpuPRF:
+# CHECK-NEXT: Number of physical registers: 72
+# CHECK-NEXT: Total number of mappings created: 0
+# CHECK-NEXT: Max number of mappings used: 0
+
+# CHECK: * Register File #2 -- JIntegerPRF:
+# CHECK-NEXT: Number of physical registers: 64
+# CHECK-NEXT: Total number of mappings created: 800
+# CHECK-NEXT: Max number of mappings used: 12
+# CHECK-NEXT: Number of optimizable moves: 100
+# CHECK-NEXT: Number of moves eliminated: 100 (100.0%)
+# CHECK-NEXT: Number of zero moves: 100 (100.0%)
+# CHECK-NEXT: Max moves eliminated per cycle: 1
+
+# CHECK: Resources:
+# CHECK-NEXT: [0] - JALU0
+# CHECK-NEXT: [1] - JALU1
+# CHECK-NEXT: [2] - JDiv
+# CHECK-NEXT: [3] - JFPA
+# CHECK-NEXT: [4] - JFPM
+# CHECK-NEXT: [5] - JFPU0
+# CHECK-NEXT: [6] - JFPU1
+# CHECK-NEXT: [7] - JLAGU
+# CHECK-NEXT: [8] - JMul
+# CHECK-NEXT: [9] - JSAGU
+# CHECK-NEXT: [10] - JSTC
+# CHECK-NEXT: [11] - JVALU0
+# CHECK-NEXT: [12] - JVALU1
+# CHECK-NEXT: [13] - JVIMUL
+
+# CHECK: Resource pressure per iteration:
+# CHECK-NEXT: [0] [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]
+# CHECK-NEXT: 2.00 2.00 - - - - - - - - - - - -
+
+# CHECK: Resource pressure by instruction:
+# CHECK-NEXT: [0] [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] Instructions:
+# CHECK-NEXT: - - - - - - - - - - - - - - xorq %rsi, %rsi
+# CHECK-NEXT: - 1.00 - - - - - - - - - - - - addq %rcx, %rcx
+# CHECK-NEXT: 1.00 - - - - - - - - - - - - - addq %rcx, %rcx
+# CHECK-NEXT: - 1.00 - - - - - - - - - - - - addq %rcx, %rcx
+# CHECK-NEXT: 1.00 - - - - - - - - - - - - - addq %rcx, %rcx
+# CHECK-NEXT: - - - - - - - - - - - - - - movl %esi, %ecx
+
+# CHECK: Timeline view:
+# CHECK-NEXT: 012
+# CHECK-NEXT: Index 0123456789
+
+# CHECK: [0,0] DR . . . xorq %rsi, %rsi
+# CHECK-NEXT: [0,1] DeER . . . addq %rcx, %rcx
+# CHECK-NEXT: [0,2] .DeER. . . addq %rcx, %rcx
+# CHECK-NEXT: [0,3] .D=eER . . addq %rcx, %rcx
+# CHECK-NEXT: [0,4] . D=eER . . addq %rcx, %rcx
+# CHECK-NEXT: [0,5] . D---R . . movl %esi, %ecx
+# CHECK-NEXT: [1,0] . D---R . . xorq %rsi, %rsi
+# CHECK-NEXT: [1,1] . DeE-R . . addq %rcx, %rcx
+# CHECK-NEXT: [1,2] . DeE-R . . addq %rcx, %rcx
+# CHECK-NEXT: [1,3] . D=eER . . addq %rcx, %rcx
+# CHECK-NEXT: [1,4] . D=eER. . addq %rcx, %rcx
+# CHECK-NEXT: [1,5] . D---R. . movl %esi, %ecx
+# CHECK-NEXT: [2,0] . .D---R . xorq %rsi, %rsi
+# CHECK-NEXT: [2,1] . .DeE-R . addq %rcx, %rcx
+# CHECK-NEXT: [2,2] . . DeE-R. addq %rcx, %rcx
+# CHECK-NEXT: [2,3] . . D=eER. addq %rcx, %rcx
+# CHECK-NEXT: [2,4] . . D=eER addq %rcx, %rcx
+# CHECK-NEXT: [2,5] . . D---R movl %esi, %ecx
+
+# CHECK: Average Wait times (based on the timeline view):
+# CHECK-NEXT: [0]: Executions
+# CHECK-NEXT: [1]: Average time spent waiting in a scheduler's queue
+# CHECK-NEXT: [2]: Average time spent waiting in a scheduler's queue while ready
+# CHECK-NEXT: [3]: Average time elapsed from WB until retire stage
+
+# CHECK: [0] [1] [2] [3]
+# CHECK-NEXT: 0. 3 0.0 0.0 2.0 xorq %rsi, %rsi
+# CHECK-NEXT: 1. 3 1.0 1.0 0.7 addq %rcx, %rcx
+# CHECK-NEXT: 2. 3 1.0 0.0 0.7 addq %rcx, %rcx
+# CHECK-NEXT: 3. 3 2.0 0.0 0.0 addq %rcx, %rcx
+# CHECK-NEXT: 4. 3 2.0 0.0 0.0 addq %rcx, %rcx
+# CHECK-NEXT: 5. 3 0.0 0.0 3.0 movl %esi, %ecx
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