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[X86] AMD Zen 3: sub-32-bit CMP also break dependencies
authorRoman Lebedev <lebedev.ri@gmail.com>
Mon, 10 May 2021 17:52:30 +0000 (20:52 +0300)
committerRoman Lebedev <lebedev.ri@gmail.com>
Mon, 10 May 2021 17:57:38 +0000 (20:57 +0300)
They measure as having the same effect as 32-bit CMP.

llvm/lib/Target/X86/X86ScheduleZnver3.td patch | blob | history
llvm/test/tools/llvm-mca/X86/Znver3/dependency-breaking-gpr.s patch | blob | history

diff --git a/llvm/lib/Target/X86/X86ScheduleZnver3.td b/llvm/lib/Target/X86/X86ScheduleZnver3.td
index b618f54..f377fb9 100644 (file)
--- a/llvm/lib/Target/X86/X86ScheduleZnver3.td
+++ b/llvm/lib/Target/X86/X86ScheduleZnver3.td
@@ -1525,7 +1525,9 @@ def Zn3WriteZeroIdiomEFLAGS : SchedWriteVariant<[
     SchedVar<MCSchedPredicate<CheckSameRegOperand<0, 1>>, [Zn3WriteZeroLatency]>,
     SchedVar<NoSchedPred,                                 [WriteALU]>
 ]>;
-def : InstRW<[Zn3WriteZeroIdiomEFLAGS], (instrs CMP32rr, CMP32rr_REV,
+def : InstRW<[Zn3WriteZeroIdiomEFLAGS], (instrs CMP8rr,  CMP8rr_REV,
+                                                CMP16rr, CMP16rr_REV,
+                                                CMP32rr, CMP32rr_REV,
                                                 CMP64rr, CMP64rr_REV)>;
 
 def : IsZeroIdiomFunction<[
@@ -1540,7 +1542,9 @@ def : IsDepBreakingFunction<[
   // GPR
   DepBreakingClass<[ SBB32rr, SBB32rr_REV,
                      SBB64rr, SBB64rr_REV ], ZeroIdiomPredicate>,
-  DepBreakingClass<[ CMP32rr, CMP32rr_REV,
+  DepBreakingClass<[ CMP8rr,  CMP8rr_REV,
+                     CMP16rr, CMP16rr_REV,
+                     CMP32rr, CMP32rr_REV,
                      CMP64rr, CMP64rr_REV ], CheckSameRegOperand<0, 1> >,
 
 
diff --git a/llvm/test/tools/llvm-mca/X86/Znver3/dependency-breaking-gpr.s b/llvm/test/tools/llvm-mca/X86/Znver3/dependency-breaking-gpr.s
index 5fc7988..4654ce1 100644 (file)
--- a/llvm/test/tools/llvm-mca/X86/Znver3/dependency-breaking-gpr.s
+++ b/llvm/test/tools/llvm-mca/X86/Znver3/dependency-breaking-gpr.s
@@ -359,7 +359,7 @@ cmovael %eax, %ecx
 
 # CHECK:      Iterations:        1000
 # CHECK-NEXT: Instructions:      3000
-# CHECK-NEXT: Total Cycles:      4005
+# CHECK-NEXT: Total Cycles:      4004
 # CHECK-NEXT: Total uOps:        4000
 
 # CHECK:      Dispatch Width:    6
@@ -377,7 +377,7 @@ cmovael %eax, %ecx
 
 # CHECK:      [1]    [2]    [3]    [4]    [5]    [6]    Instructions:
 # CHECK-NEXT:  2      4     1.00                        mulxl  %eax, %eax, %eax
-# CHECK-NEXT:  1      1     0.25                        cmpw   %ax, %ax
+# CHECK-NEXT:  1      0     0.17                        cmpw   %ax, %ax
 # CHECK-NEXT:  1      1     0.50                        cmovael        %eax, %ecx
 
 # CHECK:      Resources:
@@ -407,24 +407,24 @@ cmovael %eax, %ecx
 
 # CHECK:      Resource pressure per iteration:
 # CHECK-NEXT: [0]    [1]    [2]    [3]    [4]    [5]    [6]    [7]    [8]    [9]    [10]   [11]   [12.0] [12.1] [13]   [14.0] [14.1] [14.2] [15.0] [15.1] [15.2] [16.0] [16.1]
-# CHECK-NEXT:  -      -      -     0.67   1.00   0.67   0.67    -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -
+# CHECK-NEXT:  -      -      -     0.50   1.00    -     0.50    -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -
 
 # CHECK:      Resource pressure by instruction:
 # CHECK-NEXT: [0]    [1]    [2]    [3]    [4]    [5]    [6]    [7]    [8]    [9]    [10]   [11]   [12.0] [12.1] [13]   [14.0] [14.1] [14.2] [15.0] [15.1] [15.2] [16.0] [16.1] Instructions:
 # CHECK-NEXT:  -      -      -      -     1.00    -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -     mulxl   %eax, %eax, %eax
-# CHECK-NEXT:  -      -      -      -      -     0.67   0.33    -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -     cmpw    %ax, %ax
-# CHECK-NEXT:  -      -      -     0.67    -      -     0.33    -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -     cmovael %eax, %ecx
+# CHECK-NEXT:  -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -     cmpw    %ax, %ax
+# CHECK-NEXT:  -      -      -     0.50    -      -     0.50    -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -     cmovael %eax, %ecx
 
 # CHECK:      Timeline view:
-# CHECK-NEXT:                     012
+# CHECK-NEXT:                     01
 # CHECK-NEXT: Index     0123456789
 
-# CHECK:      [0,0]     DeeeeER   . .   mulxl  %eax, %eax, %eax
-# CHECK-NEXT: [0,1]     D====eER  . .   cmpw   %ax, %ax
-# CHECK-NEXT: [0,2]     D=====eER . .   cmovael        %eax, %ecx
-# CHECK-NEXT: [1,0]     D====eeeeER .   mulxl  %eax, %eax, %eax
-# CHECK-NEXT: [1,1]     .D=======eER.   cmpw   %ax, %ax
-# CHECK-NEXT: [1,2]     .D========eER   cmovael        %eax, %ecx
+# CHECK:      [0,0]     DeeeeER   ..   mulxl   %eax, %eax, %eax
+# CHECK-NEXT: [0,1]     D-----R   ..   cmpw    %ax, %ax
+# CHECK-NEXT: [0,2]     D====eER  ..   cmovael %eax, %ecx
+# CHECK-NEXT: [1,0]     D====eeeeER.   mulxl   %eax, %eax, %eax
+# CHECK-NEXT: [1,1]     .D--------R.   cmpw    %ax, %ax
+# CHECK-NEXT: [1,2]     .D=======eER   cmovael %eax, %ecx
 
 # CHECK:      Average Wait times (based on the timeline view):
 # CHECK-NEXT: [0]: Executions
@@ -434,15 +434,15 @@ cmovael %eax, %ecx
 
 # CHECK:            [0]    [1]    [2]    [3]
 # CHECK-NEXT: 0.     2     3.0    0.5    0.0       mulxl       %eax, %eax, %eax
-# CHECK-NEXT: 1.     2     6.5    0.0    0.0       cmpw        %ax, %ax
-# CHECK-NEXT: 2.     2     7.5    0.0    0.0       cmovael     %eax, %ecx
-# CHECK-NEXT:        2     5.7    0.2    0.0       <total>
+# CHECK-NEXT: 1.     2     0.0    0.0    6.5       cmpw        %ax, %ax
+# CHECK-NEXT: 2.     2     6.5    0.0    0.0       cmovael     %eax, %ecx
+# CHECK-NEXT:        2     3.2    0.2    2.2       <total>
 
 # CHECK:      [5] Code Region
 
 # CHECK:      Iterations:        1000
 # CHECK-NEXT: Instructions:      3000
-# CHECK-NEXT: Total Cycles:      4005
+# CHECK-NEXT: Total Cycles:      4004
 # CHECK-NEXT: Total uOps:        4000
 
 # CHECK:      Dispatch Width:    6
@@ -460,7 +460,7 @@ cmovael %eax, %ecx
 
 # CHECK:      [1]    [2]    [3]    [4]    [5]    [6]    Instructions:
 # CHECK-NEXT:  2      4     1.00                        mulxl  %eax, %eax, %eax
-# CHECK-NEXT:  1      1     0.25                        cmpb   %al, %al
+# CHECK-NEXT:  1      0     0.17                        cmpb   %al, %al
 # CHECK-NEXT:  1      1     0.50                        cmovael        %eax, %ecx
 
 # CHECK:      Resources:
@@ -490,24 +490,24 @@ cmovael %eax, %ecx
 
 # CHECK:      Resource pressure per iteration:
 # CHECK-NEXT: [0]    [1]    [2]    [3]    [4]    [5]    [6]    [7]    [8]    [9]    [10]   [11]   [12.0] [12.1] [13]   [14.0] [14.1] [14.2] [15.0] [15.1] [15.2] [16.0] [16.1]
-# CHECK-NEXT:  -      -      -     0.67   1.00   0.67   0.67    -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -
+# CHECK-NEXT:  -      -      -     0.50   1.00    -     0.50    -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -
 
 # CHECK:      Resource pressure by instruction:
 # CHECK-NEXT: [0]    [1]    [2]    [3]    [4]    [5]    [6]    [7]    [8]    [9]    [10]   [11]   [12.0] [12.1] [13]   [14.0] [14.1] [14.2] [15.0] [15.1] [15.2] [16.0] [16.1] Instructions:
 # CHECK-NEXT:  -      -      -      -     1.00    -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -     mulxl   %eax, %eax, %eax
-# CHECK-NEXT:  -      -      -      -      -     0.67   0.33    -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -     cmpb    %al, %al
-# CHECK-NEXT:  -      -      -     0.67    -      -     0.33    -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -     cmovael %eax, %ecx
+# CHECK-NEXT:  -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -     cmpb    %al, %al
+# CHECK-NEXT:  -      -      -     0.50    -      -     0.50    -      -      -      -      -      -      -      -      -      -      -      -      -      -      -      -     cmovael %eax, %ecx
 
 # CHECK:      Timeline view:
-# CHECK-NEXT:                     012
+# CHECK-NEXT:                     01
 # CHECK-NEXT: Index     0123456789
 
-# CHECK:      [0,0]     DeeeeER   . .   mulxl  %eax, %eax, %eax
-# CHECK-NEXT: [0,1]     D====eER  . .   cmpb   %al, %al
-# CHECK-NEXT: [0,2]     D=====eER . .   cmovael        %eax, %ecx
-# CHECK-NEXT: [1,0]     D====eeeeER .   mulxl  %eax, %eax, %eax
-# CHECK-NEXT: [1,1]     .D=======eER.   cmpb   %al, %al
-# CHECK-NEXT: [1,2]     .D========eER   cmovael        %eax, %ecx
+# CHECK:      [0,0]     DeeeeER   ..   mulxl   %eax, %eax, %eax
+# CHECK-NEXT: [0,1]     D-----R   ..   cmpb    %al, %al
+# CHECK-NEXT: [0,2]     D====eER  ..   cmovael %eax, %ecx
+# CHECK-NEXT: [1,0]     D====eeeeER.   mulxl   %eax, %eax, %eax
+# CHECK-NEXT: [1,1]     .D--------R.   cmpb    %al, %al
+# CHECK-NEXT: [1,2]     .D=======eER   cmovael %eax, %ecx
 
 # CHECK:      Average Wait times (based on the timeline view):
 # CHECK-NEXT: [0]: Executions
@@ -517,6 +517,6 @@ cmovael %eax, %ecx
 
 # CHECK:            [0]    [1]    [2]    [3]
 # CHECK-NEXT: 0.     2     3.0    0.5    0.0       mulxl       %eax, %eax, %eax
-# CHECK-NEXT: 1.     2     6.5    0.0    0.0       cmpb        %al, %al
-# CHECK-NEXT: 2.     2     7.5    0.0    0.0       cmovael     %eax, %ecx
-# CHECK-NEXT:        2     5.7    0.2    0.0       <total>
+# CHECK-NEXT: 1.     2     0.0    0.0    6.5       cmpb        %al, %al
+# CHECK-NEXT: 2.     2     6.5    0.0    0.0       cmovael     %eax, %ecx
+# CHECK-NEXT:        2     3.2    0.2    2.2       <total>
Domain: System / Toolchain;