Zen5 tuning part 3: scheduler tweaks

this patch adds support for new fussion in znver5 documented in the
optimization manual:

   The Zen5 microarchitecture adds support to fuse reg-reg MOV Instructions
   with certain ALU instructions. The following conditions need to be met for
   fusion to happen:
     - The MOV should be reg-reg mov with Opcode 0x89 or 0x8B
     - The MOV is followed by an ALU instruction where the MOV and ALU destination register match.
     - The ALU instruction may source only registers or immediate data. There cannot be any memory source.
     - The ALU instruction sources either the source or dest of MOV instruction.
     - If ALU instruction has 2 reg sources, they should be different.
     - The following ALU instructions can fuse with an older qualified MOV instruction:
       ADD ADC AND XOR OP SUB SBB INC DEC NOT SAL / SHL SHR SAR
       (I assume OP is OR)

I also increased issue rate from 4 to 6.  Theoretically znver5 can do more, but
with our model we can't realy use it.
Increasing issue rate to 8 leads to infinite loop in scheduler.

Finally, I also enabled fuse_alu_and_branch since it is supported by
znver5 (I think by earlier zens too).

New fussion pattern moves quite few instructions around in common code:
@@ -2210,13 +2210,13 @@
        .cfi_offset 3, -32
        leaq    63(%rsi), %rbx
        movq    %rbx, %rbp
+       shrq    $6, %rbp
+       salq    $3, %rbp
        subq    $16, %rsp
        .cfi_def_cfa_offset 48
        movq    %rdi, %r12
-       shrq    $6, %rbp
-       movq    %rsi, 8(%rsp)
-       salq    $3, %rbp
        movq    %rbp, %rdi
+       movq    %rsi, 8(%rsp)
        call    _Znwm
        movq    8(%rsp), %rsi
        movl    $0, 8(%r12)
@@ -2224,8 +2224,8 @@
        movq    %rax, (%r12)
        movq    %rbp, 32(%r12)
        testq   %rsi, %rsi
-       movq    %rsi, %rdx
        cmovns  %rsi, %rbx
+       movq    %rsi, %rdx
        sarq    $63, %rdx
        shrq    $58, %rdx
        sarq    $6, %rbx
which should help decoder bandwidth and perhaps also cache, though I was not
able to measure off-noise effect on SPEC.

gcc/ChangeLog:

	* config/i386/i386.h (TARGET_FUSE_MOV_AND_ALU): New tune.
	* config/i386/x86-tune-sched.cc (ix86_issue_rate): Updat for znver5.
	(ix86_adjust_cost): Add TODO about znver5 memory latency.
	(ix86_fuse_mov_alu_p): New.
	(ix86_macro_fusion_pair_p): Use it.
	* config/i386/x86-tune.def (X86_TUNE_FUSE_ALU_AND_BRANCH): Add ZNVER5.
	(X86_TUNE_FUSE_MOV_AND_ALU): New tune;

diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
index eabb3248ea0085409ad7dc7a18e852f967f5252a..c1ec92ffb15093e58782807671652ac8e4292b61 100644 (file)
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -430,6 +430,8 @@ extern unsigned char ix86_tune_features[X86_TUNE_LAST];
        ix86_tune_features[X86_TUNE_FUSE_CMP_AND_BRANCH_SOFLAGS]
 #define TARGET_FUSE_ALU_AND_BRANCH \
        ix86_tune_features[X86_TUNE_FUSE_ALU_AND_BRANCH]
+#define TARGET_FUSE_MOV_AND_ALU \
+       ix86_tune_features[X86_TUNE_FUSE_MOV_AND_ALU]
 #define TARGET_OPT_AGU ix86_tune_features[X86_TUNE_OPT_AGU]
 #define TARGET_AVOID_LEA_FOR_ADDR \
        ix86_tune_features[X86_TUNE_AVOID_LEA_FOR_ADDR]

diff --git a/gcc/config/i386/x86-tune-sched.cc b/gcc/config/i386/x86-tune-sched.cc
index d77298b0e34dc403600078da62ed510d524fbb95..c6d5426ae8d383e693fa80745ad8b685d954c780 100644 (file)
--- a/gcc/config/i386/x86-tune-sched.cc
+++ b/gcc/config/i386/x86-tune-sched.cc
@@ -67,7 +67,6 @@ ix86_issue_rate (void)
     case PROCESSOR_ZNVER2:
     case PROCESSOR_ZNVER3:
     case PROCESSOR_ZNVER4:
-    case PROCESSOR_ZNVER5:
     case PROCESSOR_CORE2:
     case PROCESSOR_NEHALEM:
     case PROCESSOR_SANDYBRIDGE:
@@ -91,6 +90,13 @@ ix86_issue_rate (void)
       return 5;
 
     case PROCESSOR_SAPPHIRERAPIDS:
+    /* For znver5 decoder can handle 4 or 8 instructions per cycle,
+       op cache 12 instruction/cycle, dispatch 8 instructions
+       integer rename 8 instructions and Fp 6 instructions.
+
+       The scheduler, without understanding out of order nature of the CPU
+       is unlikely going to be able to fill all of these.  */
+    case PROCESSOR_ZNVER5:
       return 6;
 
     default:
@@ -434,6 +440,8 @@ ix86_adjust_cost (rtx_insn *insn, int dep_type, rtx_insn *dep_insn, int cost,
          enum attr_unit unit = get_attr_unit (insn);
          int loadcost;
 
+         /* TODO: On znver5 complex addressing modes have
+            greater latency.  */
          if (unit == UNIT_INTEGER || unit == UNIT_UNKNOWN)
            loadcost = 4;
          else
@@ -563,6 +571,60 @@ ix86_macro_fusion_p ()
   return TARGET_FUSE_CMP_AND_BRANCH;
 }
 
+static bool
+ix86_fuse_mov_alu_p (rtx_insn *mov, rtx_insn *alu)
+{
+  /* Validate mov:
+      - It should be reg-reg move with opcode 0x89 or 0x8B.  */
+  rtx set1 = PATTERN (mov);
+  if (GET_CODE (set1) != SET
+      || !GENERAL_REG_P (SET_SRC (set1))
+      || !GENERAL_REG_P (SET_DEST (set1)))
+    return false;
+  rtx reg = SET_DEST (set1);
+  /*  - it should have 0x89 or 0x8B opcode.  */
+  if (!INTEGRAL_MODE_P (GET_MODE (reg))
+      || GET_MODE_SIZE (GET_MODE (reg)) < 2
+      || GET_MODE_SIZE (GET_MODE (reg)) > 8)
+    return false;
+  /* Validate ALU.  */
+  if (GET_CODE (PATTERN (alu)) != PARALLEL)
+    return false;
+  rtx set2 = XVECEXP (PATTERN (alu), 0, 0);
+  if (GET_CODE (set2) != SET)
+    return false;
+  /* Match one of:
+     ADD ADC AND XOR OR SUB SBB INC DEC NOT SAL SHL SHR SAR
+     We also may add insn attribute to handle some of sporadic
+     case we output those with different RTX expressions.  */
+
+  if (GET_CODE (SET_SRC (set2)) != PLUS
+      && GET_CODE (SET_SRC (set2)) != MINUS
+      && GET_CODE (SET_SRC (set2)) != XOR
+      && GET_CODE (SET_SRC (set2)) != AND
+      && GET_CODE (SET_SRC (set2)) != IOR
+      && GET_CODE (SET_SRC (set2)) != NOT
+      && GET_CODE (SET_SRC (set2)) != ASHIFT
+      && GET_CODE (SET_SRC (set2)) != ASHIFTRT
+      && GET_CODE (SET_SRC (set2)) != LSHIFTRT)
+    return false;
+  rtx op0 = XEXP (SET_SRC (set2), 0);
+  rtx op1 = GET_CODE (SET_SRC (set2)) != NOT ? XEXP (SET_SRC (set2), 1) : NULL;
+  /* One of operands should be register.  */
+  if (op1 && (!REG_P (op0) || REGNO (op0) != REGNO (reg)))
+    std::swap (op0, op1);
+  if (!REG_P (op0) || REGNO (op1) != REGNO (reg))
+    return false;
+  if (op1
+      && !REG_P (op1)
+      && !x86_64_immediate_operand (op1, VOIDmode))
+    return false;
+  /* Only one of two paramters must be move destination.  */
+  if (op1 && REG_P (op1) && REGNO (op1) == REGNO (reg))
+    return false;
+  return true;
+}
+
 /* Check whether current microarchitecture support macro fusion
    for insn pair "CONDGEN + CONDJMP". Refer to
    "Intel Architectures Optimization Reference Manual". */
@@ -570,6 +632,9 @@ ix86_macro_fusion_p ()
 bool
 ix86_macro_fusion_pair_p (rtx_insn *condgen, rtx_insn *condjmp)
 {
+  if (TARGET_FUSE_MOV_AND_ALU
+      && ix86_fuse_mov_alu_p (condgen, condjmp))
+    return true;
   rtx src, dest;
   enum rtx_code ccode;
   rtx compare_set = NULL_RTX, test_if, cond;

diff --git a/gcc/config/i386/x86-tune.def b/gcc/config/i386/x86-tune.def
index ed26136faee52c9ea0f54fdb7f039091a0c791f9..d7e2ad7fd250b71a494feb6e3c910b9910276b0e 100644 (file)
--- a/gcc/config/i386/x86-tune.def
+++ b/gcc/config/i386/x86-tune.def
@@ -143,10 +143,17 @@ DEF_TUNE (X86_TUNE_FUSE_CMP_AND_BRANCH_SOFLAGS, "fuse_cmp_and_branch_soflags",
 
 /* X86_TUNE_FUSE_ALU_AND_BRANCH: Fuse alu with a subsequent conditional
    jump instruction when the alu instruction produces the CCFLAG consumed by
-   the conditional jump instruction. */
+   the conditional jump instruction.
+
+   TODO: znver5 supports fusing with SUB, ADD, INC, DEC, OR, AND,
+   There is also limitation for immediate and displacement supported.  */
 DEF_TUNE (X86_TUNE_FUSE_ALU_AND_BRANCH, "fuse_alu_and_branch",
-                 m_SANDYBRIDGE | m_CORE_AVX2 | m_ZHAOXIN | m_GENERIC)
+         m_SANDYBRIDGE | m_CORE_AVX2 | m_ZHAOXIN | m_GENERIC | m_ZNVER5)
 
+/* X86_TUNE_FUSE_MOV_AND_ALU: mov and alu in case mov is reg-reg mov
+   and the destination is used by alu.  alu must be one of
+   ADD, ADC, AND, XOR, OR, SUB, SBB, INC, DEC, NOT, SAL, SHL, SHR, SAR.  */
+DEF_TUNE (X86_TUNE_FUSE_MOV_AND_ALU, "fuse_mov_and_alu", m_ZNVER5)
 
 /*****************************************************************************/
 /* Function prologue, epilogue and function calling sequences.               */