| Message ID | CAHFci28vO8iv_DvD+KqM2M=7e+EkR_fh6Msvc1dbFqg2eWnyNg@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On Mon, Jul 10, 2017 at 10:24 AM, Bin.Cheng <amker.cheng@gmail.com> wrote: > On Tue, Jun 27, 2017 at 11:49 AM, Bin Cheng <Bin.Cheng@arm.com> wrote: >> Hi, >> This is a followup patch better handling below case: >> for (i = 0; i < n; i++) >> { >> a[i] = 1; >> a[i+2] = 2; >> } >> Instead of generating root variables by loading from memory and propagating with PHI >> nodes, like: >> t0 = a[0]; >> t1 = a[1]; >> for (i = 0; i < n; i++) >> { >> a[i] = 1; >> t2 = 2; >> t0 = t1; >> t1 = t2; >> } >> a[n] = t0; >> a[n+1] = t1; >> We can simply store loop invariant values after loop body if we know loop iterates more >> than chain->length times, like: >> for (i = 0; i < n; i++) >> { >> a[i] = 1; >> } >> a[n] = 2; >> a[n+1] = 2; >> >> Bootstrap(O2/O3) in patch series on x86_64 and AArch64. Is it OK? > Update patch wrto changes in previous patch. > Bootstrap and test on x86_64 and AArch64. Is it OK? + if (TREE_CODE (val) == INTEGER_CST || TREE_CODE (val) == REAL_CST) + continue; Please use CONSTANT_CLASS_P (val) instead. I suppose VECTOR_CST or FIXED_CST would be ok as well for example. Ok with that change. Did we eventually optimize this in followup passes previously? Richard. > Thanks, > bin >> >> Thanks, >> bin >> 2017-06-21 Bin Cheng <bin.cheng@arm.com> >> >> * tree-predcom.c: (struct chain): Handle store-store chain in which >> stores for elimination only store loop invariant values. >> (execute_pred_commoning_chain): Ditto. >> (prepare_initializers_chain_store_elim): Ditto. >> (prepare_finalizers): Ditto. >> (is_inv_store_elimination_chain): New function. >> (initialize_root_vars_store_elim_1): New function.
On Tue, Jul 25, 2017 at 12:48 PM, Richard Biener <richard.guenther@gmail.com> wrote: > On Mon, Jul 10, 2017 at 10:24 AM, Bin.Cheng <amker.cheng@gmail.com> wrote: >> On Tue, Jun 27, 2017 at 11:49 AM, Bin Cheng <Bin.Cheng@arm.com> wrote: >>> Hi, >>> This is a followup patch better handling below case: >>> for (i = 0; i < n; i++) >>> { >>> a[i] = 1; >>> a[i+2] = 2; >>> } >>> Instead of generating root variables by loading from memory and propagating with PHI >>> nodes, like: >>> t0 = a[0]; >>> t1 = a[1]; >>> for (i = 0; i < n; i++) >>> { >>> a[i] = 1; >>> t2 = 2; >>> t0 = t1; >>> t1 = t2; >>> } >>> a[n] = t0; >>> a[n+1] = t1; >>> We can simply store loop invariant values after loop body if we know loop iterates more >>> than chain->length times, like: >>> for (i = 0; i < n; i++) >>> { >>> a[i] = 1; >>> } >>> a[n] = 2; >>> a[n+1] = 2; >>> >>> Bootstrap(O2/O3) in patch series on x86_64 and AArch64. Is it OK? >> Update patch wrto changes in previous patch. >> Bootstrap and test on x86_64 and AArch64. Is it OK? > > + if (TREE_CODE (val) == INTEGER_CST || TREE_CODE (val) == REAL_CST) > + continue; > > Please use CONSTANT_CLASS_P (val) instead. I suppose VECTOR_CST or > FIXED_CST would be ok as well for example. > > Ok with that change. Did we eventually optimize this in followup > passes previously? Probably not? Given below test: int a[10000], b[10000], c[10000]; int f(void) { int i, n = 100; int t0 = a[0]; int t1 = a[1]; for (i = 0; i < n; i++) { a[i] = 1; int t2 = 2; t0 = t1; t1 = t2; } a[n] = t0; a[n+1] = t1; return 0; } The optimized dump is as: <bb 2> [1.00%] [count: INV]: t1_8 = a[1]; ivtmp.9_17 = (unsigned long) &a; _16 = ivtmp.9_17 + 400; <bb 3> [99.00%] [count: INV]: # t1_20 = PHI <2(3), t1_8(2)> # ivtmp.9_2 = PHI <ivtmp.9_1(3), ivtmp.9_17(2)> _15 = (void *) ivtmp.9_2; MEM[base: _15, offset: 0B] = 1; ivtmp.9_1 = ivtmp.9_2 + 4; if (ivtmp.9_1 != _16) goto <bb 3>; [98.99%] [count: INV] else goto <bb 4>; [1.01%] [count: INV] <bb 4> [1.00%] [count: INV]: a[100] = t1_20; a[101] = 2; return 0; We now eliminate one phi and leave another behind. It is vrp1/dce2 when the phi is eliminated. Thanks, bin
On Tue, Jul 25, 2017 at 2:38 PM, Bin.Cheng <amker.cheng@gmail.com> wrote: > On Tue, Jul 25, 2017 at 12:48 PM, Richard Biener > <richard.guenther@gmail.com> wrote: >> On Mon, Jul 10, 2017 at 10:24 AM, Bin.Cheng <amker.cheng@gmail.com> wrote: >>> On Tue, Jun 27, 2017 at 11:49 AM, Bin Cheng <Bin.Cheng@arm.com> wrote: >>>> Hi, >>>> This is a followup patch better handling below case: >>>> for (i = 0; i < n; i++) >>>> { >>>> a[i] = 1; >>>> a[i+2] = 2; >>>> } >>>> Instead of generating root variables by loading from memory and propagating with PHI >>>> nodes, like: >>>> t0 = a[0]; >>>> t1 = a[1]; >>>> for (i = 0; i < n; i++) >>>> { >>>> a[i] = 1; >>>> t2 = 2; >>>> t0 = t1; >>>> t1 = t2; >>>> } >>>> a[n] = t0; >>>> a[n+1] = t1; >>>> We can simply store loop invariant values after loop body if we know loop iterates more >>>> than chain->length times, like: >>>> for (i = 0; i < n; i++) >>>> { >>>> a[i] = 1; >>>> } >>>> a[n] = 2; >>>> a[n+1] = 2; >>>> >>>> Bootstrap(O2/O3) in patch series on x86_64 and AArch64. Is it OK? >>> Update patch wrto changes in previous patch. >>> Bootstrap and test on x86_64 and AArch64. Is it OK? >> >> + if (TREE_CODE (val) == INTEGER_CST || TREE_CODE (val) == REAL_CST) >> + continue; >> >> Please use CONSTANT_CLASS_P (val) instead. I suppose VECTOR_CST or >> FIXED_CST would be ok as well for example. >> >> Ok with that change. Did we eventually optimize this in followup >> passes previously? > Probably not? Given below test: > > int a[10000], b[10000], c[10000]; > int f(void) > { > int i, n = 100; > int t0 = a[0]; > int t1 = a[1]; > for (i = 0; i < n; i++) > { > a[i] = 1; > int t2 = 2; > t0 = t1; > t1 = t2; > } > a[n] = t0; > a[n+1] = t1; > return 0; > } > The optimized dump is as: > > <bb 2> [1.00%] [count: INV]: > t1_8 = a[1]; > ivtmp.9_17 = (unsigned long) &a; > _16 = ivtmp.9_17 + 400; > > <bb 3> [99.00%] [count: INV]: > # t1_20 = PHI <2(3), t1_8(2)> > # ivtmp.9_2 = PHI <ivtmp.9_1(3), ivtmp.9_17(2)> > _15 = (void *) ivtmp.9_2; > MEM[base: _15, offset: 0B] = 1; > ivtmp.9_1 = ivtmp.9_2 + 4; > if (ivtmp.9_1 != _16) > goto <bb 3>; [98.99%] [count: INV] > else > goto <bb 4>; [1.01%] [count: INV] > > <bb 4> [1.00%] [count: INV]: > a[100] = t1_20; > a[101] = 2; > return 0; > > We now eliminate one phi and leave another behind. It is vrp1/dce2 > when the phi is eliminated. Ok, I see. Maybe worth filing a missed optimization PR. Richard. > Thanks, > bin
On Tue, Jul 25, 2017 at 1:57 PM, Richard Biener <richard.guenther@gmail.com> wrote: > On Tue, Jul 25, 2017 at 2:38 PM, Bin.Cheng <amker.cheng@gmail.com> wrote: >> On Tue, Jul 25, 2017 at 12:48 PM, Richard Biener >> <richard.guenther@gmail.com> wrote: >>> On Mon, Jul 10, 2017 at 10:24 AM, Bin.Cheng <amker.cheng@gmail.com> wrote: >>>> On Tue, Jun 27, 2017 at 11:49 AM, Bin Cheng <Bin.Cheng@arm.com> wrote: >>>>> Hi, >>>>> This is a followup patch better handling below case: >>>>> for (i = 0; i < n; i++) >>>>> { >>>>> a[i] = 1; >>>>> a[i+2] = 2; >>>>> } >>>>> Instead of generating root variables by loading from memory and propagating with PHI >>>>> nodes, like: >>>>> t0 = a[0]; >>>>> t1 = a[1]; >>>>> for (i = 0; i < n; i++) >>>>> { >>>>> a[i] = 1; >>>>> t2 = 2; >>>>> t0 = t1; >>>>> t1 = t2; >>>>> } >>>>> a[n] = t0; >>>>> a[n+1] = t1; >>>>> We can simply store loop invariant values after loop body if we know loop iterates more >>>>> than chain->length times, like: >>>>> for (i = 0; i < n; i++) >>>>> { >>>>> a[i] = 1; >>>>> } >>>>> a[n] = 2; >>>>> a[n+1] = 2; >>>>> >>>>> Bootstrap(O2/O3) in patch series on x86_64 and AArch64. Is it OK? >>>> Update patch wrto changes in previous patch. >>>> Bootstrap and test on x86_64 and AArch64. Is it OK? >>> >>> + if (TREE_CODE (val) == INTEGER_CST || TREE_CODE (val) == REAL_CST) >>> + continue; >>> >>> Please use CONSTANT_CLASS_P (val) instead. I suppose VECTOR_CST or >>> FIXED_CST would be ok as well for example. >>> >>> Ok with that change. Did we eventually optimize this in followup >>> passes previously? >> Probably not? Given below test: >> >> int a[10000], b[10000], c[10000]; >> int f(void) >> { >> int i, n = 100; >> int t0 = a[0]; >> int t1 = a[1]; >> for (i = 0; i < n; i++) >> { >> a[i] = 1; >> int t2 = 2; >> t0 = t1; >> t1 = t2; >> } >> a[n] = t0; >> a[n+1] = t1; >> return 0; >> } >> The optimized dump is as: >> >> <bb 2> [1.00%] [count: INV]: >> t1_8 = a[1]; >> ivtmp.9_17 = (unsigned long) &a; >> _16 = ivtmp.9_17 + 400; >> >> <bb 3> [99.00%] [count: INV]: >> # t1_20 = PHI <2(3), t1_8(2)> >> # ivtmp.9_2 = PHI <ivtmp.9_1(3), ivtmp.9_17(2)> >> _15 = (void *) ivtmp.9_2; >> MEM[base: _15, offset: 0B] = 1; >> ivtmp.9_1 = ivtmp.9_2 + 4; >> if (ivtmp.9_1 != _16) >> goto <bb 3>; [98.99%] [count: INV] >> else >> goto <bb 4>; [1.01%] [count: INV] >> >> <bb 4> [1.00%] [count: INV]: >> a[100] = t1_20; >> a[101] = 2; >> return 0; >> >> We now eliminate one phi and leave another behind. It is vrp1/dce2 >> when the phi is eliminated. > > Ok, I see. Maybe worth filing a missed optimization PR. Right, PR81549 filed. Thanks, bin > > Richard. > >> Thanks, >> bin
On Tue, Jul 25, 2017 at 12:48 PM, Richard Biener <richard.guenther@gmail.com> wrote: > On Mon, Jul 10, 2017 at 10:24 AM, Bin.Cheng <amker.cheng@gmail.com> wrote: >> On Tue, Jun 27, 2017 at 11:49 AM, Bin Cheng <Bin.Cheng@arm.com> wrote: >>> Hi, >>> This is a followup patch better handling below case: >>> for (i = 0; i < n; i++) >>> { >>> a[i] = 1; >>> a[i+2] = 2; >>> } >>> Instead of generating root variables by loading from memory and propagating with PHI >>> nodes, like: >>> t0 = a[0]; >>> t1 = a[1]; >>> for (i = 0; i < n; i++) >>> { >>> a[i] = 1; >>> t2 = 2; >>> t0 = t1; >>> t1 = t2; >>> } >>> a[n] = t0; >>> a[n+1] = t1; >>> We can simply store loop invariant values after loop body if we know loop iterates more >>> than chain->length times, like: >>> for (i = 0; i < n; i++) >>> { >>> a[i] = 1; >>> } >>> a[n] = 2; >>> a[n+1] = 2; >>> >>> Bootstrap(O2/O3) in patch series on x86_64 and AArch64. Is it OK? >> Update patch wrto changes in previous patch. >> Bootstrap and test on x86_64 and AArch64. Is it OK? > > + if (TREE_CODE (val) == INTEGER_CST || TREE_CODE (val) == REAL_CST) > + continue; > > Please use CONSTANT_CLASS_P (val) instead. I suppose VECTOR_CST or > FIXED_CST would be ok as well for example. > > Ok with that change. Did we eventually optimize this in followup Patch revised as suggested. I retested whole patch set and applied as 250665 ~ 250670. Will keep eyes on possible breakage in next couple weeks. Thanks, bin > passes previously? > > Richard. > >> Thanks, >> bin >>> >>> Thanks, >>> bin >>> 2017-06-21 Bin Cheng <bin.cheng@arm.com> >>> >>> * tree-predcom.c: (struct chain): Handle store-store chain in which >>> stores for elimination only store loop invariant values. >>> (execute_pred_commoning_chain): Ditto. >>> (prepare_initializers_chain_store_elim): Ditto. >>> (prepare_finalizers): Ditto. >>> (is_inv_store_elimination_chain): New function. >>> (initialize_root_vars_store_elim_1): New function.
From 7b03b8fe27ce144b557cfd10143e2531323164db Mon Sep 17 00:00:00 2001 From: Bin Cheng <binche01@e108451-lin.cambridge.arm.com> Date: Wed, 5 Jul 2017 17:30:38 +0100 Subject: [PATCH 6/6] inv-store-elimination-20170627.txt --- gcc/tree-predcom.c | 131 ++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 125 insertions(+), 6 deletions(-) diff --git a/gcc/tree-predcom.c b/gcc/tree-predcom.c index ac0d0d0..d2738a5 100644 --- a/gcc/tree-predcom.c +++ b/gcc/tree-predcom.c @@ -331,6 +331,10 @@ typedef struct chain /* True if this chain was combined together with some other chain. */ unsigned combined : 1; + + /* True if this is store elimination chain and eliminated stores store + loop invariant value into memory. */ + unsigned inv_store_elimination : 1; } *chain_p; @@ -1634,6 +1638,98 @@ initialize_root_vars (struct loop *loop, chain_p chain, bitmap tmp_vars) } } +/* For inter-iteration store elimination CHAIN in LOOP, returns true if + all stores to be eliminated store loop invariant values into memory. + In this case, we can use these invariant values directly after LOOP. */ + +static bool +is_inv_store_elimination_chain (struct loop *loop, chain_p chain) +{ + if (chain->length == 0 || chain->type != CT_STORE_STORE) + return false; + + gcc_assert (!chain->has_max_use_after); + + /* If loop iterates for unknown times or fewer times than chain->lenght, + we still need to setup root variable and propagate it with PHI node. */ + tree niters = number_of_latch_executions (loop); + if (TREE_CODE (niters) != INTEGER_CST || wi::leu_p (niters, chain->length)) + return false; + + /* Check stores in chain for elimination if they only store loop invariant + values. */ + for (unsigned i = 0; i < chain->length; i++) + { + dref a = get_chain_last_ref_at (chain, i); + if (a == NULL) + continue; + + gimple *def_stmt, *stmt = a->stmt; + if (!gimple_assign_single_p (stmt)) + return false; + + tree val = gimple_assign_rhs1 (stmt); + if (TREE_CLOBBER_P (val)) + return false; + + if (TREE_CODE (val) == INTEGER_CST || TREE_CODE (val) == REAL_CST) + continue; + + if (TREE_CODE (val) != SSA_NAME) + return false; + + def_stmt = SSA_NAME_DEF_STMT (val); + if (gimple_nop_p (def_stmt)) + continue; + + if (flow_bb_inside_loop_p (loop, gimple_bb (def_stmt))) + return false; + } + return true; +} + +/* Creates root variables for store elimination CHAIN in which stores for + elimination only store loop invariant values. In this case, we neither + need to load root variables before loop nor propagate it with PHI nodes. */ + +static void +initialize_root_vars_store_elim_1 (chain_p chain) +{ + tree var; + unsigned i, n = chain->length; + + chain->vars.create (n); + chain->vars.safe_grow_cleared (n); + + /* Initialize root value for eliminated stores at each distance. */ + for (i = 0; i < n; i++) + { + dref a = get_chain_last_ref_at (chain, i); + if (a == NULL) + continue; + + var = gimple_assign_rhs1 (a->stmt); + chain->vars[a->distance] = var; + } + + /* We don't propagate values with PHI nodes, so manually propagate value + to bubble positions. */ + var = chain->vars[0]; + for (i = 1; i < n; i++) + { + if (chain->vars[i] != NULL_TREE) + { + var = chain->vars[i]; + continue; + } + chain->vars[i] = var; + } + + /* Revert the vector. */ + for (i = 0; i < n / 2; i++) + std::swap (chain->vars[i], chain->vars[n - i - 1]); +} + /* Creates root variables for store elimination CHAIN in which stores for elimination store loop variant values. In this case, we may need to load root variables before LOOP and propagate it with PHI nodes. Uids @@ -1957,10 +2053,20 @@ execute_pred_commoning_chain (struct loop *loop, chain_p chain, { if (chain->length > 0) { - /* For inter-iteration store elimination chain, set up the - variables by loading from memory before loop, copying from rhs - of stores for elimination and propagate it with PHI nodes. */ - initialize_root_vars_store_elim_2 (loop, chain, tmp_vars); + if (chain->inv_store_elimination) + { + /* If dead stores in this chain only store loop invariant + values, we can simply record the invariant value and use + it directly after loop. */ + initialize_root_vars_store_elim_1 (chain); + } + else + { + /* If dead stores in this chain store loop variant values, + we need to set up the variables by loading from memory + before loop and propagating it with PHI nodes. */ + initialize_root_vars_store_elim_2 (loop, chain, tmp_vars); + } /* For inter-iteration store elimination chain, stores at each distance in loop's last (chain->length - 1) iterations can't @@ -2661,7 +2767,7 @@ try_combine_chains (vec<chain_p> *chains) otherwise. */ static bool -prepare_initializers_chain_store_elim (struct loop *, chain_p chain) +prepare_initializers_chain_store_elim (struct loop *loop, chain_p chain) { unsigned i, n = chain->length; @@ -2674,6 +2780,15 @@ prepare_initializers_chain_store_elim (struct loop *, chain_p chain) if (n == 0 && chain->type == CT_STORE_STORE) return true; + /* For store elimination chain, there is nothing to initialize if stores + to be eliminated only store loop invariant values into memory. */ + if (chain->type == CT_STORE_STORE + && is_inv_store_elimination_chain (loop, chain)) + { + chain->inv_store_elimination = true; + return true; + } + chain->inits.create (n); chain->inits.safe_grow_cleared (n); @@ -2866,7 +2981,11 @@ prepare_finalizers (struct loop *loop, vec<chain_p> chains) if (prepare_finalizers_chain (loop, chain)) { i++; - loop_closed_ssa = true; + /* We don't corrupt loop closed ssa form for store elimination + chain if eliminated stores only store loop invariant values + into memory. */ + if (!chain->inv_store_elimination) + loop_closed_ssa |= (!chain->inv_store_elimination); } else { -- 1.9.1