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tcg: Reduce copies for plugin_gen_mem_callbacks 
We only need to make copies for loads, when the destination
overlaps the address.  For now, only eliminate the copy for
stores and 128-bit loads.

Rename plugin_prep_mem_callbacks to plugin_maybe_preserve_addr,
returning NULL if no copy is made.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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@rth7680
rth7680 committed May 16, 2023
1 parent c0e46de commit 1935c32
Showing 1 changed file with 20 additions and 18 deletions.
38 changes: 20 additions & 18 deletions tcg/tcg-op-ldst.c
View file
Expand Up @@ -114,7 +114,8 @@ static void tcg_gen_req_mo(TCGBar type)
}
}

static inline TCGv plugin_prep_mem_callbacks(TCGv vaddr)
/* Only required for loads, where value might overlap addr. */
static TCGv plugin_maybe_preserve_addr(TCGv vaddr)
{
#ifdef CONFIG_PLUGIN
if (tcg_ctx->plugin_insn != NULL) {
Expand All @@ -124,17 +125,20 @@ static inline TCGv plugin_prep_mem_callbacks(TCGv vaddr)
return temp;
}
#endif
return vaddr;
return NULL;
}

static void plugin_gen_mem_callbacks(TCGv vaddr, MemOpIdx oi,
enum qemu_plugin_mem_rw rw)
static void
plugin_gen_mem_callbacks(TCGv copy_addr, TCGv orig_addr, MemOpIdx oi,
enum qemu_plugin_mem_rw rw)
{
#ifdef CONFIG_PLUGIN
if (tcg_ctx->plugin_insn != NULL) {
qemu_plugin_meminfo_t info = make_plugin_meminfo(oi, rw);
plugin_gen_empty_mem_callback(vaddr, info);
tcg_temp_free(vaddr);
plugin_gen_empty_mem_callback(copy_addr ? : orig_addr, info);
if (copy_addr) {
tcg_temp_free(copy_addr);
}
}
#endif
}
Expand All @@ -143,6 +147,7 @@ void tcg_gen_qemu_ld_i32(TCGv_i32 val, TCGv addr, TCGArg idx, MemOp memop)
{
MemOp orig_memop;
MemOpIdx oi;
TCGv copy_addr;

tcg_gen_req_mo(TCG_MO_LD_LD | TCG_MO_ST_LD);
memop = tcg_canonicalize_memop(memop, 0, 0);
Expand All @@ -157,9 +162,9 @@ void tcg_gen_qemu_ld_i32(TCGv_i32 val, TCGv addr, TCGArg idx, MemOp memop)
}
}

addr = plugin_prep_mem_callbacks(addr);
copy_addr = plugin_maybe_preserve_addr(addr);
gen_ldst_i32(INDEX_op_qemu_ld_i32, val, addr, memop, idx);
plugin_gen_mem_callbacks(addr, oi, QEMU_PLUGIN_MEM_R);
plugin_gen_mem_callbacks(copy_addr, addr, oi, QEMU_PLUGIN_MEM_R);

if ((orig_memop ^ memop) & MO_BSWAP) {
switch (orig_memop & MO_SIZE) {
Expand Down Expand Up @@ -202,13 +207,12 @@ void tcg_gen_qemu_st_i32(TCGv_i32 val, TCGv addr, TCGArg idx, MemOp memop)
memop &= ~MO_BSWAP;
}

addr = plugin_prep_mem_callbacks(addr);
if (TCG_TARGET_HAS_qemu_st8_i32 && (memop & MO_SIZE) == MO_8) {
gen_ldst_i32(INDEX_op_qemu_st8_i32, val, addr, memop, idx);
} else {
gen_ldst_i32(INDEX_op_qemu_st_i32, val, addr, memop, idx);
}
plugin_gen_mem_callbacks(addr, oi, QEMU_PLUGIN_MEM_W);
plugin_gen_mem_callbacks(NULL, addr, oi, QEMU_PLUGIN_MEM_W);

if (swap) {
tcg_temp_free_i32(swap);
Expand All @@ -219,6 +223,7 @@ void tcg_gen_qemu_ld_i64(TCGv_i64 val, TCGv addr, TCGArg idx, MemOp memop)
{
MemOp orig_memop;
MemOpIdx oi;
TCGv copy_addr;

if (TCG_TARGET_REG_BITS == 32 && (memop & MO_SIZE) < MO_64) {
tcg_gen_qemu_ld_i32(TCGV_LOW(val), addr, idx, memop);
Expand All @@ -243,9 +248,9 @@ void tcg_gen_qemu_ld_i64(TCGv_i64 val, TCGv addr, TCGArg idx, MemOp memop)
}
}

addr = plugin_prep_mem_callbacks(addr);
copy_addr = plugin_maybe_preserve_addr(addr);
gen_ldst_i64(INDEX_op_qemu_ld_i64, val, addr, memop, idx);
plugin_gen_mem_callbacks(addr, oi, QEMU_PLUGIN_MEM_R);
plugin_gen_mem_callbacks(copy_addr, addr, oi, QEMU_PLUGIN_MEM_R);

if ((orig_memop ^ memop) & MO_BSWAP) {
int flags = (orig_memop & MO_SIGN
Expand Down Expand Up @@ -300,9 +305,8 @@ void tcg_gen_qemu_st_i64(TCGv_i64 val, TCGv addr, TCGArg idx, MemOp memop)
memop &= ~MO_BSWAP;
}

addr = plugin_prep_mem_callbacks(addr);
gen_ldst_i64(INDEX_op_qemu_st_i64, val, addr, memop, idx);
plugin_gen_mem_callbacks(addr, oi, QEMU_PLUGIN_MEM_W);
plugin_gen_mem_callbacks(NULL, addr, oi, QEMU_PLUGIN_MEM_W);

if (swap) {
tcg_temp_free_i64(swap);
Expand Down Expand Up @@ -419,7 +423,6 @@ void tcg_gen_qemu_ld_i128(TCGv_i128 val, TCGv addr, TCGArg idx, MemOp memop)
tcg_debug_assert((memop & MO_SIGN) == 0);

tcg_gen_req_mo(TCG_MO_LD_LD | TCG_MO_ST_LD);
addr = plugin_prep_mem_callbacks(addr);

/* TODO: For now, force 32-bit hosts to use the helper. */
if (TCG_TARGET_HAS_qemu_ldst_i128 && TCG_TARGET_REG_BITS == 64) {
Expand Down Expand Up @@ -490,7 +493,7 @@ void tcg_gen_qemu_ld_i128(TCGv_i128 val, TCGv addr, TCGArg idx, MemOp memop)
maybe_free_addr64(a64);
}

plugin_gen_mem_callbacks(addr, oi, QEMU_PLUGIN_MEM_R);
plugin_gen_mem_callbacks(NULL, addr, oi, QEMU_PLUGIN_MEM_R);
}

void tcg_gen_qemu_st_i128(TCGv_i128 val, TCGv addr, TCGArg idx, MemOp memop)
Expand All @@ -501,7 +504,6 @@ void tcg_gen_qemu_st_i128(TCGv_i128 val, TCGv addr, TCGArg idx, MemOp memop)
tcg_debug_assert((memop & MO_SIGN) == 0);

tcg_gen_req_mo(TCG_MO_ST_LD | TCG_MO_ST_ST);
addr = plugin_prep_mem_callbacks(addr);

/* TODO: For now, force 32-bit hosts to use the helper. */

Expand Down Expand Up @@ -572,7 +574,7 @@ void tcg_gen_qemu_st_i128(TCGv_i128 val, TCGv addr, TCGArg idx, MemOp memop)
maybe_free_addr64(a64);
}

plugin_gen_mem_callbacks(addr, oi, QEMU_PLUGIN_MEM_W);
plugin_gen_mem_callbacks(NULL, addr, oi, QEMU_PLUGIN_MEM_W);
}

static void tcg_gen_ext_i32(TCGv_i32 ret, TCGv_i32 val, MemOp opc)
Expand Down

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