Greetings,
Here is a new revision of the tree portions of this patch. I moved the
pattern recognizer to expand, and added additional logic to look for the
same pattern in gimple form. I added two more tests to verify the new
logic.
I didn't run into any problems with the RTL CSE phases. I can't recall
for certain what caused me to abandon the expand version previously.
There may not have been good reason; too many versions to keep track of
and too many interruptions, I suppose. In any case, I'm much happier
having this code in the expander.
Paolo's RTL logic for unpropagating the zero-offset case is not going to
work out as is. It causes a number of performance degradations, which I
suspect are due to the pass reordering. That's a separate issue,
though, and not needed for this patch.
Bootstrapped and regression-tested on powerpc64-linux. SPEC cpu2000
shows a number of small improvements and no significant degradations.
SPEC cpu2006 testing is pending.
Thanks,
Bill
2011-10-18 Bill Schmidt <wschm...@linux.vnet.ibm.com>
gcc:
PR rtl-optimization/46556
* expr.c (tree-pretty-print.h): New include.
(restructure_base_and_offset): New function.
(restructure_mem_ref): New function.
(expand_expr_real_1): In MEM_REF case, attempt restructure_mem_ref
first. In normal_inner_ref case, attempt restructure_base_and_offset
first.
* Makefile.in: Update dependences for expr.o.
gcc/testsuite:
PR rtl-optimization/46556
* gcc.dg/tree-ssa-pr46556-1.c: New test.
* gcc.dg/tree-ssa-pr46556-2.c: Likewise.
* gcc.dg/tree-ssa-pr46556-3.c: Likewise.
* gcc.dg/tree-ssa-pr46556-4.c: Likewise.
* gcc.dg/tree-ssa-pr46556-5.c: Likewise.
Index: gcc/testsuite/gcc.dg/tree-ssa/pr46556-1.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/pr46556-1.c (revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/pr46556-1.c (revision 0)
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-expand" } */
+
+struct x
+{
+ int a[16];
+ int b[16];
+ int c[16];
+};
+
+extern void foo (int, int, int);
+
+void
+f (struct x *p, unsigned int n)
+{
+ foo (p->a[n], p->c[n], p->b[n]);
+}
+
+/* { dg-final { scan-rtl-dump-times "\\(mem/s:SI \\(plus:" 2 "expand" } } */
+/* { dg-final { scan-rtl-dump-times "const_int 128" 1 "expand" } } */
+/* { dg-final { scan-rtl-dump-times "const_int 64 \\\[0x40\\\]\\)\\) \\\[" 1
"expand" } } */
+/* { dg-final { cleanup-rtl-dump "expand" } } */
Index: gcc/testsuite/gcc.dg/tree-ssa/pr46556-2.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/pr46556-2.c (revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/pr46556-2.c (revision 0)
@@ -0,0 +1,26 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-expand" } */
+
+struct x
+{
+ int a[16];
+ int b[16];
+ int c[16];
+};
+
+extern void foo (int, int, int);
+
+void
+f (struct x *p, unsigned int n)
+{
+ foo (p->a[n], p->c[n], p->b[n]);
+ if (n > 12)
+ foo (p->a[n], p->c[n], p->b[n]);
+ else if (n > 3)
+ foo (p->b[n], p->a[n], p->c[n]);
+}
+
+/* { dg-final { scan-rtl-dump-times "\\(mem/s:SI \\(plus:" 6 "expand" } } */
+/* { dg-final { scan-rtl-dump-times "const_int 128" 3 "expand" } } */
+/* { dg-final { scan-rtl-dump-times "const_int 64 \\\[0x40\\\]\\)\\) \\\[" 3
"expand" } } */
+/* { dg-final { cleanup-rtl-dump "expand" } } */
Index: gcc/testsuite/gcc.dg/tree-ssa/pr46556-3.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/pr46556-3.c (revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/pr46556-3.c (revision 0)
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-expand" } */
+struct x
+{
+ int a[16];
+ int b[16];
+ int c[16];
+};
+
+extern void foo (int, int, int);
+
+void
+f (struct x *p, unsigned int n)
+{
+ foo (p->a[n], p->c[n], p->b[n]);
+ if (n > 3)
+ {
+ foo (p->a[n], p->c[n], p->b[n]);
+ if (n > 12)
+ foo (p->b[n], p->a[n], p->c[n]);
+ }
+}
+
+/* { dg-final { scan-rtl-dump-times "\\(mem/s:SI \\(plus:" 6 "expand" } } */
+/* { dg-final { scan-rtl-dump-times "const_int 128" 3 "expand" } } */
+/* { dg-final { scan-rtl-dump-times "const_int 64 \\\[0x40\\\]\\)\\) \\\[" 3
"expand" } } */
+/* { dg-final { cleanup-rtl-dump "expand" } } */
Index: gcc/testsuite/gcc.dg/tree-ssa/pr46556-4.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/pr46556-4.c (revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/pr46556-4.c (revision 0)
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-expand" } */
+
+struct x
+{
+ int a[16];
+ int b[16];
+ int c[16];
+};
+
+extern void foo (int, int, int);
+
+void
+f (struct x *p, unsigned int n)
+{
+ foo (*((int *)p + n*4), *((int *)p + 32 + n*4), *((int *)p + 16 + n*4));
+ if (n > 3)
+ {
+ foo (*((int *)p + n*4), *((int *)p + 32 + n*4), *((int *)p + 16 + n*4));
+ if (n > 12)
+ foo (*((int *)p + 16 + n*4), *((int *)p + n*4), *((int *)p + 32 + n*4));
+ }
+}
+
+/* { dg-final { scan-rtl-dump-times "\\(mem:SI \\(plus:" 6 "expand" } } */
+/* { dg-final { scan-rtl-dump-times "const_int 128" 3 "expand" } } */
+/* { dg-final { scan-rtl-dump-times "const_int 64 \\\[0x40\\\]\\)\\) \\\[" 3
"expand" } } */
+/* { dg-final { cleanup-rtl-dump "expand" } } */
Index: gcc/testsuite/gcc.dg/tree-ssa/pr46556-5.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/pr46556-5.c (revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/pr46556-5.c (revision 0)
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-expand" } */
+/* { dg-skip-if "" { lp64 } { "*" } { "-m32" } } */
+/* { dg-skip-if "" { llp64 } { "*" } { "-m32" } } */
+
+struct x
+{
+ int a[16];
+ int b[16];
+ int c[16];
+};
+
+extern void foo (int, int, int);
+
+void
+f (struct x *p, unsigned int n)
+{
+ foo (*((int *)p + n * 4),
+ *((int *)p + (n + 8) * 4),
+ *((int *)p + (n + 4) * 4));
+ if (n > 3)
+ {
+ foo (*((int *)p + n * 4),
+ *((int *)p + (n + 8) * 4),
+ *((int *)p + (n + 4) * 4));
+ if (n > 12)
+ foo (*((int *)p + (n + 4) * 4),
+ *((int *)p + n * 4),
+ *((int *)p + (n + 8) * 4));
+ }
+}
+
+/* { dg-final { scan-rtl-dump-times "\\(mem:SI \\(plus:" 6 "expand" } } */
+/* { dg-final { scan-rtl-dump-times "const_int 128" 3 "expand" } } */
+/* { dg-final { scan-rtl-dump-times "const_int 64 \\\[0x40\\\]\\)\\) \\\[" 3
"expand" } } */
+/* { dg-final { cleanup-rtl-dump "expand" } } */
Index: gcc/expr.c
===================================================================
--- gcc/expr.c (revision 180138)
+++ gcc/expr.c (working copy)
@@ -56,6 +56,7 @@ along with GCC; see the file COPYING3. If not see
#include "ssaexpand.h"
#include "target-globals.h"
#include "params.h"
+#include "tree-pretty-print.h"
/* Decide whether a function's arguments should be processed
from first to last or from last to first.
@@ -7648,7 +7649,157 @@ expand_constructor (tree exp, rtx target, enum exp
return target;
}
+/* Given BASE, OFFSET, and BITPOS derived from EXPR, determine whether
+ there is a profitable opportunity to restructure address arithmetic
+ within BASE and OFFSET. If so, produce such a restructuring and
+ return it. */
+/* TODO: This belongs more properly in a separate pass that performs
+ general strength reduction on straight-line code. Eventually move
+ this there. */
+static tree
+restructure_base_and_offset (tree expr, tree base, tree offset,
+ HOST_WIDE_INT bitpos)
+{
+ tree mult_op0, mult_op1, t1, t2, offset_type, mult_expr, add_expr, mem_ref;
+ double_int c, c1, c2, c3, c4;
+
+ /* Look for the following pattern:
+
+ base = MEM_REF (T1, C1);
+ offset = MULT_EXPR (PLUS_EXPR (T2, C2), C3)
+ bitpos = C4 * BITS_PER_UNIT
+
+ If found, convert it to:
+
+ MEM_REF (POINTER_PLUS_EXPR (T1, MULT_EXPR (T2, C3)),
+ C1 + (C2 * C3) + C4)
+ */
+ if (!base
+ || !offset
+ || TREE_CODE (base) != MEM_REF
+ || TREE_CODE (offset) != MULT_EXPR)
+ return NULL_TREE;
+
+ mult_op0 = TREE_OPERAND (offset, 0);
+ mult_op1 = TREE_OPERAND (offset, 1);
+
+ if (TREE_CODE (mult_op0) != PLUS_EXPR
+ || TREE_CODE (mult_op1) != INTEGER_CST
+ || TREE_CODE (TREE_OPERAND (mult_op0, 1)) != INTEGER_CST)
+ return NULL_TREE;
+
+ t1 = TREE_OPERAND (base, 0);
+ t2 = TREE_OPERAND (mult_op0, 0);
+ c1 = mem_ref_offset (base);
+ c2 = tree_to_double_int (TREE_OPERAND (mult_op0, 1));
+ c3 = tree_to_double_int (mult_op1);
+ c4 = uhwi_to_double_int (bitpos / BITS_PER_UNIT);
+ c = double_int_add (double_int_add (c1, double_int_mul (c2, c3)), c4);
+
+ offset_type = TREE_TYPE (TREE_OPERAND (base, 1));
+
+ mult_expr = fold_build2 (MULT_EXPR, sizetype, t2,
+ double_int_to_tree (sizetype, c3));
+
+ add_expr = fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (t1), t1, mult_expr);
+
+ mem_ref = fold_build2 (MEM_REF, TREE_TYPE (expr), add_expr,
+ double_int_to_tree (offset_type, c));
+ return mem_ref;
+}
+
+/* Look for a hidden array reference in memory reference EXP. If found,
+ return a revised memory reference that restructures addressability
+ to combine constants. */
+/* TODO: This belongs more properly in a separate pass that performs
+ general strength reduction on straight-line code. Eventually move
+ this there. */
+
+static tree
+restructure_mem_ref (tree exp)
+{
+ tree s2, s3, t1, t2, offset_type, mult_expr, add_expr;
+ tree s2_op0, s2_op1, s3_op0, s3_op1, result;
+ gimple s1_stmt, s2_stmt, s3_stmt;
+ double_int c1, c2, c3, c;
+
+ /* Currently we look for the following pattern, where each Si is an
+ SSA name, each Tj is an arbitrary tree, and each Ck is an integer
+ constant:
+
+ S3 = T2 + C2;
+ S2 = S3 * C3;
+ S1 = T1 ptr+ S2;
+ exp = MEM_REF (S1, C1);
+
+ This is rewritten as:
+
+ exp = MEM_REF (T1 ptr+ (T2 * C3)), C1 + C2 * C3);
+
+ */
+ if (TREE_CODE (TREE_OPERAND (exp, 0)) != SSA_NAME)
+ return NULL_TREE;
+
+ /* We don't use get_def_for_expr for S1 because TER doesn't forward
+ S1 in some situations where this transform is useful, such as
+ when S1 is the base of two MEM_REFs fitting the pattern. */
+ s1_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (exp, 0));
+
+ if (!s1_stmt
+ || !is_gimple_assign (s1_stmt)
+ || gimple_assign_rhs_code (s1_stmt) != POINTER_PLUS_EXPR)
+ return NULL_TREE;
+
+ c1 = mem_ref_offset (exp);
+ t1 = gimple_assign_rhs1 (s1_stmt);
+ s2 = gimple_assign_rhs2 (s1_stmt);
+
+ if (TREE_CODE (s2) != SSA_NAME)
+ return NULL_TREE;
+
+ s2_stmt = get_def_for_expr (s2, MULT_EXPR);
+
+ if (!s2_stmt)
+ return NULL_TREE;
+
+ s2_op0 = gimple_assign_rhs1 (s2_stmt);
+ s2_op1 = gimple_assign_rhs2 (s2_stmt);
+
+ if (TREE_CODE (s2_op1) != INTEGER_CST)
+ return NULL_TREE;
+
+ s3 = s2_op0;
+ c3 = tree_to_double_int (s2_op1);
+ s3_stmt = get_def_for_expr (s3, PLUS_EXPR);
+
+ if (!s3_stmt)
+ return NULL_TREE;
+
+ s3_op0 = gimple_assign_rhs1 (s3_stmt);
+ s3_op1 = gimple_assign_rhs2 (s3_stmt);
+
+ if (TREE_CODE (s3_op1) != INTEGER_CST)
+ return NULL_TREE;
+
+ t2 = s3_op0;
+ c2 = tree_to_double_int (s3_op1);
+ c = double_int_add (c1, double_int_mul (c2, c3));
+
+ offset_type = TREE_TYPE (TREE_OPERAND (exp, 1));
+
+ mult_expr = fold_build2 (MULT_EXPR, sizetype, t2,
+ double_int_to_tree (sizetype, c3));
+
+ add_expr = fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (t1), t1, mult_expr);
+
+ result = build2 (MEM_REF, TREE_TYPE (exp), add_expr,
+ double_int_to_tree (offset_type, c));
+
+ return result;
+}
+
+
/* expand_expr: generate code for computing expression EXP.
An rtx for the computed value is returned. The value is never null.
In the case of a void EXP, const0_rtx is returned.
@@ -9313,6 +9464,28 @@ expand_expr_real_1 (tree exp, rtx target, enum mac
gimple def_stmt;
enum insn_code icode;
unsigned align;
+ tree tem;
+
+ /* Attempt to restructure a hidden array reference, such
+ as *(p + (n + k) * s). This generates dead code, so
+ require -O2. */
+ if (optimize > 1
+ && mode != BLKmode
+ && ((tem = restructure_mem_ref (exp)) != NULL_TREE))
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "\nRestructured memory reference:\n");
+ fprintf (dump_file, " Original reference: ");
+ print_generic_expr (dump_file, exp, TDF_VOPS|TDF_MEMSYMS);
+ fprintf (dump_file, "\n Replacement: ");
+ print_generic_expr (dump_file, tem, TDF_VOPS|TDF_MEMSYMS);
+ }
+ copy_ref_info (tem, exp);
+ exp = tem;
+ base = TREE_OPERAND (exp, 0);
+ }
+
/* Handle expansion of non-aliased memory with non-BLKmode. That
might end up in a register. */
if (TREE_CODE (base) == ADDR_EXPR)
@@ -9584,7 +9757,7 @@ expand_expr_real_1 (tree exp, rtx target, enum mac
{
enum machine_mode mode1, mode2;
HOST_WIDE_INT bitsize, bitpos;
- tree offset;
+ tree offset, tem2;
int volatilep = 0, must_force_mem;
bool packedp = false;
tree tem = get_inner_reference (exp, &bitsize, &bitpos, &offset,
@@ -9601,6 +9774,36 @@ expand_expr_real_1 (tree exp, rtx target, enum mac
&& DECL_PACKED (TREE_OPERAND (exp, 1))))
packedp = true;
+ /* Attempt to restructure the base and offset to combine constants.
+ Bitfield references should eventually be lowered prior to this
+ point and are not dealt with. Skip BLKmode aggregates as well.
+ This generates dead code, so require -O2. */
+ if (optimize > 1
+ && code != BIT_FIELD_REF
+ && (code != COMPONENT_REF
+ || !DECL_BIT_FIELD (TREE_OPERAND (exp, 1)))
+ && TYPE_MODE (TREE_TYPE (exp)) != BLKmode
+ && bitpos % BITS_PER_UNIT == 0
+ && ((tem2 = restructure_base_and_offset (exp, tem, offset, bitpos))
+ != NULL_TREE))
+ {
+ copy_ref_info (tem2, exp);
+ tem = tem2;
+ /* The offset and bitpos were absorbed into the new MEM_REF, so
+ make sure we don't add them in again. */
+ offset = NULL_TREE;
+ bitpos = 0;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "\nRestructured inner reference:\n");
+ fprintf (dump_file, " Original reference: ");
+ print_generic_expr (dump_file, exp, TDF_VOPS|TDF_MEMSYMS);
+ fprintf (dump_file, "\n Replacement: ");
+ print_generic_expr (dump_file, tem, TDF_VOPS|TDF_MEMSYMS);
+ }
+ }
+
/* If TEM's type is a union of variable size, pass TARGET to the inner
computation, since it will need a temporary and TARGET is known
to have to do. This occurs in unchecked conversion in Ada. */
Index: gcc/Makefile.in
===================================================================
--- gcc/Makefile.in (revision 180138)
+++ gcc/Makefile.in (working copy)
@@ -2926,7 +2926,7 @@ expr.o : expr.c $(CONFIG_H) $(SYSTEM_H) coretypes.
reload.h langhooks.h intl.h $(TM_P_H) $(TARGET_H) \
tree-iterator.h gt-expr.h $(MACHMODE_H) $(TIMEVAR_H) $(TREE_FLOW_H) \
$(TREE_PASS_H) $(DF_H) $(DIAGNOSTIC_H) vecprim.h $(SSAEXPAND_H) \
- $(PARAMS_H) $(COMMON_TARGET_H)
+ $(PARAMS_H) $(COMMON_TARGET_H) tree-pretty-print.h
dojump.o : dojump.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H)
$(TREE_H) \
$(FLAGS_H) $(FUNCTION_H) $(EXPR_H) $(OPTABS_H) $(INSN_ATTR_H) insn-config.h
\
langhooks.h $(GGC_H) gt-dojump.h vecprim.h $(BASIC_BLOCK_H) output.h
