[PATCH 12/14] target/i386: use compiler builtin to compute PF

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From: Paolo Bonzini <pbonzini@redhat.com>
To: qemu-devel@nongnu.org
Cc: richard.henderson@linaro.org
Subject: [PATCH 12/14] target/i386: use compiler builtin to compute PF
Date: Mon, 28 Oct 2024 16:18:49 +0100	[thread overview]
Message-ID: <20241028151851.376355-13-pbonzini@redhat.com> (raw)
In-Reply-To: <20241028151851.376355-1-pbonzini@redhat.com>

This removes the 256 byte parity table from the executable.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/qemu/host-utils.h                |  9 ++++++
 target/i386/tcg/helper-tcg.h             |  6 +++-
 target/i386/tcg/cc_helper_template.h.inc | 20 +++++++-------
 target/i386/tcg/cc_helper.c              | 35 ------------------------
 target/i386/tcg/int_helper.c             |  4 +--
 5 files changed, 26 insertions(+), 48 deletions(-)

diff --git a/include/qemu/host-utils.h b/include/qemu/host-utils.h
index ead97d354d6..4d28fa22cfa 100644
--- a/include/qemu/host-utils.h
+++ b/include/qemu/host-utils.h
@@ -313,6 +313,15 @@ static inline int ctpop8(uint8_t val)
     return __builtin_popcount(val);
 }
 
+/*
+ * parity8 - return the parity (1 = odd) of an 8-bit value.
+ * @val: The value to search
+ */
+static inline int parity8(uint8_t val)
+{
+    return __builtin_parity(val);
+}
+
 /**
  * ctpop16 - count the population of one bits in a 16-bit value.
  * @val: The value to search
diff --git a/target/i386/tcg/helper-tcg.h b/target/i386/tcg/helper-tcg.h
index 15d6c6f8b4f..696d6ef016f 100644
--- a/target/i386/tcg/helper-tcg.h
+++ b/target/i386/tcg/helper-tcg.h
@@ -21,6 +21,7 @@
 #define I386_HELPER_TCG_H
 
 #include "exec/exec-all.h"
+#include "qemu/host-utils.h"
 
 /* Maximum instruction code size */
 #define TARGET_MAX_INSN_SIZE 16
@@ -87,7 +88,10 @@ G_NORETURN void x86_cpu_do_unaligned_access(CPUState *cs, vaddr vaddr,
 #endif
 
 /* cc_helper.c */
-extern const uint8_t parity_table[256];
+static inline unsigned int compute_pf(uint8_t x)
+{
+    return !parity8(x) * CC_P;
+}
 
 /* misc_helper.c */
 void cpu_load_eflags(CPUX86State *env, int eflags, int update_mask);
diff --git a/target/i386/tcg/cc_helper_template.h.inc b/target/i386/tcg/cc_helper_template.h.inc
index 4cbbc73c3cd..8af8b8539f9 100644
--- a/target/i386/tcg/cc_helper_template.h.inc
+++ b/target/i386/tcg/cc_helper_template.h.inc
@@ -45,7 +45,7 @@ static uint32_t glue(compute_all_add, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
     DATA_TYPE src2 = dst - src1;
 
     cf = dst < src1;
-    pf = parity_table[(uint8_t)dst];
+    pf = compute_pf(dst);
     af = (dst ^ src1 ^ src2) & CC_A;
     zf = (dst == 0) * CC_Z;
     sf = lshift(dst, 8 - DATA_BITS) & CC_S;
@@ -65,7 +65,7 @@ static uint32_t glue(compute_all_adc, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1,
     DATA_TYPE src2 = dst - src1 - src3;
 
     cf = (src3 ? dst <= src1 : dst < src1);
-    pf = parity_table[(uint8_t)dst];
+    pf = compute_pf(dst);
     af = (dst ^ src1 ^ src2) & 0x10;
     zf = (dst == 0) << 6;
     sf = lshift(dst, 8 - DATA_BITS) & 0x80;
@@ -85,7 +85,7 @@ static uint32_t glue(compute_all_sub, SUFFIX)(DATA_TYPE dst, DATA_TYPE src2)
     DATA_TYPE src1 = dst + src2;
 
     cf = src1 < src2;
-    pf = parity_table[(uint8_t)dst];
+    pf = compute_pf(dst);
     af = (dst ^ src1 ^ src2) & CC_A;
     zf = (dst == 0) * CC_Z;
     sf = lshift(dst, 8 - DATA_BITS) & CC_S;
@@ -107,7 +107,7 @@ static uint32_t glue(compute_all_sbb, SUFFIX)(DATA_TYPE dst, DATA_TYPE src2,
     DATA_TYPE src1 = dst + src2 + src3;
 
     cf = (src3 ? src1 <= src2 : src1 < src2);
-    pf = parity_table[(uint8_t)dst];
+    pf = compute_pf(dst);
     af = (dst ^ src1 ^ src2) & 0x10;
     zf = (dst == 0) << 6;
     sf = lshift(dst, 8 - DATA_BITS) & 0x80;
@@ -128,7 +128,7 @@ static uint32_t glue(compute_all_logic, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
     uint32_t cf, pf, af, zf, sf, of;
 
     cf = 0;
-    pf = parity_table[(uint8_t)dst];
+    pf = compute_pf(dst);
     af = 0;
     zf = (dst == 0) * CC_Z;
     sf = lshift(dst, 8 - DATA_BITS) & CC_S;
@@ -144,7 +144,7 @@ static uint32_t glue(compute_all_inc, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
     cf = src1;
     src1 = dst - 1;
     src2 = 1;
-    pf = parity_table[(uint8_t)dst];
+    pf = compute_pf(dst);
     af = (dst ^ src1 ^ src2) & CC_A;
     zf = (dst == 0) * CC_Z;
     sf = lshift(dst, 8 - DATA_BITS) & CC_S;
@@ -160,7 +160,7 @@ static uint32_t glue(compute_all_dec, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
     cf = src1;
     src1 = dst + 1;
     src2 = 1;
-    pf = parity_table[(uint8_t)dst];
+    pf = compute_pf(dst);
     af = (dst ^ src1 ^ src2) & CC_A;
     zf = (dst == 0) * CC_Z;
     sf = lshift(dst, 8 - DATA_BITS) & CC_S;
@@ -173,7 +173,7 @@ static uint32_t glue(compute_all_shl, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
     uint32_t cf, pf, af, zf, sf, of;
 
     cf = (src1 >> (DATA_BITS - 1)) & CC_C;
-    pf = parity_table[(uint8_t)dst];
+    pf = compute_pf(dst);
     af = 0; /* undefined */
     zf = (dst == 0) * CC_Z;
     sf = lshift(dst, 8 - DATA_BITS) & CC_S;
@@ -192,7 +192,7 @@ static uint32_t glue(compute_all_sar, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
     uint32_t cf, pf, af, zf, sf, of;
 
     cf = src1 & 1;
-    pf = parity_table[(uint8_t)dst];
+    pf = compute_pf(dst);
     af = 0; /* undefined */
     zf = (dst == 0) * CC_Z;
     sf = lshift(dst, 8 - DATA_BITS) & CC_S;
@@ -209,7 +209,7 @@ static uint32_t glue(compute_all_mul, SUFFIX)(DATA_TYPE dst, target_long src1)
     uint32_t cf, pf, af, zf, sf, of;
 
     cf = (src1 != 0);
-    pf = parity_table[(uint8_t)dst];
+    pf = compute_pf(dst);
     af = 0; /* undefined */
     zf = (dst == 0) * CC_Z;
     sf = lshift(dst, 8 - DATA_BITS) & CC_S;
diff --git a/target/i386/tcg/cc_helper.c b/target/i386/tcg/cc_helper.c
index 1b83775a914..f1940b40927 100644
--- a/target/i386/tcg/cc_helper.c
+++ b/target/i386/tcg/cc_helper.c
@@ -22,41 +22,6 @@
 #include "exec/helper-proto.h"
 #include "helper-tcg.h"
 
-const uint8_t parity_table[256] = {
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    CC_P, 0, 0, CC_P, 0, CC_P, CC_P, 0,
-    0, CC_P, CC_P, 0, CC_P, 0, 0, CC_P,
-};
-
 #define SHIFT 0
 #include "cc_helper_template.h.inc"
 #undef SHIFT
diff --git a/target/i386/tcg/int_helper.c b/target/i386/tcg/int_helper.c
index e1f92405282..1a02e9d8434 100644
--- a/target/i386/tcg/int_helper.c
+++ b/target/i386/tcg/int_helper.c
@@ -237,7 +237,7 @@ void helper_daa(CPUX86State *env)
     env->regs[R_EAX] = (env->regs[R_EAX] & ~0xff) | al;
     /* well, speed is not an issue here, so we compute the flags by hand */
     eflags |= (al == 0) << 6; /* zf */
-    eflags |= parity_table[al]; /* pf */
+    eflags |= compute_pf(al);
     eflags |= (al & 0x80); /* sf */
     CC_SRC = eflags;
     CC_OP = CC_OP_EFLAGS;
@@ -269,7 +269,7 @@ void helper_das(CPUX86State *env)
     env->regs[R_EAX] = (env->regs[R_EAX] & ~0xff) | al;
     /* well, speed is not an issue here, so we compute the flags by hand */
     eflags |= (al == 0) << 6; /* zf */
-    eflags |= parity_table[al]; /* pf */
+    eflags |= compute_pf(al);
     eflags |= (al & 0x80); /* sf */
     CC_SRC = eflags;
     CC_OP = CC_OP_EFLAGS;
-- 
2.47.0

next prev parent reply	other threads:[~2024-10-28 15:21 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-28 15:18 [PATCH v2 00/14] target/i386: miscellaneous flags improvements Paolo Bonzini
2024-10-28 15:18 ` [PATCH 01/14] target/i386: use tcg_gen_ext_tl when applicable Paolo Bonzini
2024-10-28 15:18 ` [PATCH 02/14] target/i386: Tidy cc_op_str usage Paolo Bonzini
2024-10-28 15:18 ` [PATCH 03/14] target/i386: remove CC_OP_CLR Paolo Bonzini
2024-10-28 15:18 ` [PATCH 04/14] target/i386: Rearrange CCOp Paolo Bonzini
2024-10-28 15:18 ` [PATCH 05/14] target/i386: Introduce cc_op_size Paolo Bonzini
2024-10-28 15:18 ` [PATCH 06/14] target/i386: Wrap cc_op_live with a validity check Paolo Bonzini
2024-10-28 15:18 ` [PATCH 07/14] target/i386: optimize computation of ZF from CC_OP_DYNAMIC Paolo Bonzini
2024-10-29 15:43   ` Richard Henderson
2024-10-28 15:18 ` [PATCH 08/14] target/i386: optimize TEST+Jxx sequences Paolo Bonzini
2024-10-28 15:18 ` [PATCH 09/14] target/i386: add a few more trivial CCPrepare cases Paolo Bonzini
2024-10-28 15:18 ` [PATCH 10/14] target/i386: add a note about gen_jcc1 Paolo Bonzini
2024-10-29 15:44   ` Richard Henderson
2024-10-28 15:18 ` [PATCH 11/14] target/i386: make flag variables unsigned Paolo Bonzini
2024-10-28 15:18 ` Paolo Bonzini [this message]
2024-10-29 15:45   ` [PATCH 12/14] target/i386: use compiler builtin to compute PF Richard Henderson
2024-10-28 15:18 ` [PATCH 13/14] target/i386: use higher-precision arithmetic to compute CF Paolo Bonzini
2024-10-29 15:46   ` Richard Henderson
2024-10-28 15:18 ` [PATCH 14/14] target/i386: use + to put flags together Paolo Bonzini
2024-10-29 15:46   ` Richard Henderson

find likely ancestor, descendant, or conflicting patches for this message:
( dfblob:ead97d354d dfblob:4d28fa22cf dfblob:15d6c6f8b4
dfblob:696d6ef016 dfblob:4cbbc73c3c dfblob:8af8b8539f dfblob:1b83775a91
dfblob:f1940b4092 dfblob:e1f9240528 dfblob:1a02e9d843 )
 OR (
bs:"[PATCH 12/14] target/i386: use compiler builtin to compute PF" )
	(help)

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