[v2] match: Fix wrong code due to `(a ? e : f) !=/== (b ? e : f)` patterns [PR116120]
Checks
| Context |
Check |
Description |
| linaro-tcwg-bot/tcwg_gcc_build--master-arm |
success
|
Build passed
|
| linaro-tcwg-bot/tcwg_gcc_build--master-aarch64 |
success
|
Build passed
|
Commit Message
When this pattern was converted from being only dealing with 0/-1, we missed that if `e == f` is true
then the optimization is wrong and needs an extra check for that.
This changes the patterns to be:
/* (a ? x : y) != (b ? x : y) --> (a^b & (x != y)) ? TRUE : FALSE */
/* (a ? x : y) == (b ? x : y) --> (a^b & (x != y)) ? FALSE : TRUE */
/* (a ? x : y) != (b ? y : x) --> (a^b | (x == y)) ? FALSE : TRUE */
/* (a ? x : y) == (b ? y : x) --> (a^b | (x == y)) ? TRUE : FALSE */
Also this can't be done if the X can be a NaNs either. Since that changes the value there too.
This still produces better code than the original case and in many cases (x != y) will
still reduce to either false or true.
With this change we also need to make sure `a`, `b` and the resulting types are all
the same for the same reason as the previous patch.
I updated (well added) to the testcases to make sure there are the right amount of
comparisons left.
Changes since v1:
* v2: Fixed the testcase names and fixed dg-run to be `dg-do run`. Added a check for HONORS_NANS too.
Bootstrapped and tested on x86_64-linux-gnu with no regressions.
PR tree-optimization/116120
gcc/ChangeLog:
* match.pd (`(a ? x : y) eq/ne (b ? x : y)`): Add test for `x != y`
in result.
(`(a ? x : y) eq/ne (b ? y : x)`): Add test for `x == y` in result.
gcc/testsuite/ChangeLog:
* g++.dg/tree-ssa/pr111150.C: Add extra checks on the test.
* gcc.dg/tree-ssa/pr111150-1.c: Likewise.
* gcc.dg/tree-ssa/pr111150.c: Likewise.
* g++.dg/torture/pr116120-1.C: New test.
* g++.dg/torture/pr116120-2.C: New test.
Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
---
gcc/match.pd | 23 ++++++----
gcc/testsuite/g++.dg/torture/pr116120-1.C | 32 +++++++++++++
gcc/testsuite/g++.dg/torture/pr116120-2.C | 53 ++++++++++++++++++++++
gcc/testsuite/g++.dg/tree-ssa/pr111150.C | 10 ++++
gcc/testsuite/gcc.dg/tree-ssa/pr111150-1.c | 9 ++++
gcc/testsuite/gcc.dg/tree-ssa/pr111150.c | 1 +
6 files changed, 120 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/torture/pr116120-1.C
create mode 100644 gcc/testsuite/g++.dg/torture/pr116120-2.C
Comments
On Thu, Aug 1, 2024 at 12:30 AM Andrew Pinski <quic_apinski@quicinc.com> wrote:
>
> When this pattern was converted from being only dealing with 0/-1, we missed that if `e == f` is true
> then the optimization is wrong and needs an extra check for that.
>
> This changes the patterns to be:
> /* (a ? x : y) != (b ? x : y) --> (a^b & (x != y)) ? TRUE : FALSE */
> /* (a ? x : y) == (b ? x : y) --> (a^b & (x != y)) ? FALSE : TRUE */
> /* (a ? x : y) != (b ? y : x) --> (a^b | (x == y)) ? FALSE : TRUE */
> /* (a ? x : y) == (b ? y : x) --> (a^b | (x == y)) ? TRUE : FALSE */
>
> Also this can't be done if the X can be a NaNs either. Since that changes the value there too.
>
> This still produces better code than the original case and in many cases (x != y) will
> still reduce to either false or true.
>
> With this change we also need to make sure `a`, `b` and the resulting types are all
> the same for the same reason as the previous patch.
>
> I updated (well added) to the testcases to make sure there are the right amount of
> comparisons left.
>
> Changes since v1:
> * v2: Fixed the testcase names and fixed dg-run to be `dg-do run`. Added a check for HONORS_NANS too.
>
> Bootstrapped and tested on x86_64-linux-gnu with no regressions.
OK
> PR tree-optimization/116120
>
> gcc/ChangeLog:
>
> * match.pd (`(a ? x : y) eq/ne (b ? x : y)`): Add test for `x != y`
> in result.
> (`(a ? x : y) eq/ne (b ? y : x)`): Add test for `x == y` in result.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/tree-ssa/pr111150.C: Add extra checks on the test.
> * gcc.dg/tree-ssa/pr111150-1.c: Likewise.
> * gcc.dg/tree-ssa/pr111150.c: Likewise.
> * g++.dg/torture/pr116120-1.C: New test.
> * g++.dg/torture/pr116120-2.C: New test.
>
> Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
> ---
> gcc/match.pd | 23 ++++++----
> gcc/testsuite/g++.dg/torture/pr116120-1.C | 32 +++++++++++++
> gcc/testsuite/g++.dg/torture/pr116120-2.C | 53 ++++++++++++++++++++++
> gcc/testsuite/g++.dg/tree-ssa/pr111150.C | 10 ++++
> gcc/testsuite/gcc.dg/tree-ssa/pr111150-1.c | 9 ++++
> gcc/testsuite/gcc.dg/tree-ssa/pr111150.c | 1 +
> 6 files changed, 120 insertions(+), 8 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/torture/pr116120-1.C
> create mode 100644 gcc/testsuite/g++.dg/torture/pr116120-2.C
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 881a827860f..c9c8478d286 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -5632,21 +5632,28 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (vec_cond (bit_and (bit_not @0) @1) @2 @3)))
> #endif
>
> -/* (a ? x : y) != (b ? x : y) --> (a^b) ? TRUE : FALSE */
> -/* (a ? x : y) == (b ? x : y) --> (a^b) ? FALSE : TRUE */
> -/* (a ? x : y) != (b ? y : x) --> (a^b) ? FALSE : TRUE */
> -/* (a ? x : y) == (b ? y : x) --> (a^b) ? TRUE : FALSE */
> +/* (a ? x : y) != (b ? x : y) --> (a^b & (x != y)) ? TRUE : FALSE */
> +/* (a ? x : y) == (b ? x : y) --> (a^b & (x != y)) ? FALSE : TRUE */
> +/* (a ? x : y) != (b ? y : x) --> (a^b | (x == y)) ? FALSE : TRUE */
> +/* (a ? x : y) == (b ? y : x) --> (a^b | (x == y)) ? TRUE : FALSE */
> +/* These are only valid if x and y don't have NaNs. */
> (for cnd (cond vec_cond)
> (for eqne (eq ne)
> (simplify
> (eqne:c (cnd @0 @1 @2) (cnd @3 @1 @2))
> - (if (types_match (TREE_TYPE (@0), TREE_TYPE (@3)))
> - (cnd (bit_xor @0 @3) { constant_boolean_node (eqne == NE_EXPR, type); }
> + (if (!HONOR_NANS (@1)
> + && types_match (TREE_TYPE (@0), TREE_TYPE (@3))
> + && types_match (type, TREE_TYPE (@0)))
> + (cnd (bit_and (bit_xor @0 @3) (ne:type @1 @2))
> + { constant_boolean_node (eqne == NE_EXPR, type); }
> { constant_boolean_node (eqne != NE_EXPR, type); })))
> (simplify
> (eqne:c (cnd @0 @1 @2) (cnd @3 @2 @1))
> - (if (types_match (TREE_TYPE (@0), TREE_TYPE (@3)))
> - (cnd (bit_xor @0 @3) { constant_boolean_node (eqne != NE_EXPR, type); }
> + (if (!HONOR_NANS (@1)
> + && types_match (TREE_TYPE (@0), TREE_TYPE (@3))
> + && types_match (type, TREE_TYPE (@0)))
> + (cnd (bit_ior (bit_xor @0 @3) (eq:type @1 @2))
> + { constant_boolean_node (eqne != NE_EXPR, type); }
> { constant_boolean_node (eqne == NE_EXPR, type); })))))
>
> /* Canonicalize mask ? { 0, ... } : { -1, ...} to ~mask if the mask
> diff --git a/gcc/testsuite/g++.dg/torture/pr116120-1.C b/gcc/testsuite/g++.dg/torture/pr116120-1.C
> new file mode 100644
> index 00000000000..209946f17a4
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/torture/pr116120-1.C
> @@ -0,0 +1,32 @@
> +// { dg-do run }
> +// PR tree-optimization/116120
> +
> +// The optimization for `(a ? x : y) != (b ? x : y)`
> +// missed that x and y could be the same value.
> +
> +typedef int v4si __attribute((__vector_size__(1 * sizeof(int))));
> +v4si f1(v4si a, v4si b, v4si c, v4si d, v4si e, v4si f) {
> + v4si X = a == b ? e : f;
> + v4si Y = c == d ? e : f;
> + return (X != Y); // ~(X == Y ? -1 : 0) (x ^ Y)
> +}
> +
> +int f2(int a, int b, int c, int d, int e, int f) {
> + int X = a == b ? e : f;
> + int Y = c == d ? e : f;
> + return (X != Y) ? -1 : 0; // ~(X == Y ? -1 : 0) (x ^ Y)
> +}
> +
> +int main()
> +{
> + v4si a = {0};
> + v4si b = {0}; // a == b, true
> + v4si c = {2};
> + v4si d = {3}; // c == b, false
> + v4si e = {0};
> + v4si f = e;
> + v4si r = f1(a,b,c,d,e, f);
> + int r1 = f2(a[0], b[0], c[0], d[0], e[0], f[0]);
> + if (r[0] != r1)
> + __builtin_abort();
> +}
> diff --git a/gcc/testsuite/g++.dg/torture/pr116120-2.C b/gcc/testsuite/g++.dg/torture/pr116120-2.C
> new file mode 100644
> index 00000000000..e9fee17a262
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/torture/pr116120-2.C
> @@ -0,0 +1,53 @@
> +// { dg-do run }
> +// PR tree-optimization/116120
> +
> +// The optimization for `(a ? x : y) == (b ? x : y)`
> +// missed that x and y could be the same value
> +// This can't be done if x and y support NaNs since `NaN == NaN` is always false
> +// And dominates the whole expression rather than supporting it.
> +
> +typedef int v1si __attribute((__vector_size__(1 * sizeof(int))));
> +typedef float v1sf __attribute((__vector_size__(1 * sizeof(float))));
> +
> +v1si f1(v1si a, v1si b, v1si c, v1si d, v1sf e, v1sf f) __attribute__((noinline));
> +v1si f1(v1si a, v1si b, v1si c, v1si d, v1sf e, v1sf f) {
> + v1sf X = a == b ? e : f;
> + v1sf Y = c == d ? f : e;
> + return (X == Y); // ~(X == Y ? -1 : 0) (x ^ Y)
> +}
> +
> +int f2(int a, int b, int c, int d, float e, float f) __attribute__((noinline));
> +int f2(int a, int b, int c, int d, float e, float f) {
> + float X = a == b ? e : f;
> + float Y = c == d ? f : e;
> + return (X == Y) ? -1 : 0; // ~(X == Y ? -1 : 0) (x ^ Y)
> +}
> +
> +int main()
> +{
> + v1si a = {0};
> + v1si b = {0}; // a == b, true
> + v1si c = {2};
> + v1si d = {3}; // c == b, false
> + v1sf e;
> + v1sf f;
> +
> + /* Test signed 0s. */
> + e = (v1sf){0.0};
> + f = -e;
> + v1si r = f1(a,b,c,d,e, f);
> + int r1 = f2(a[0], b[0], c[0], d[0], e[0], f[0]);
> + if (r[0] != r1)
> + __builtin_abort();
> +
> + /* Test NaNs */
> +#if __FLT_HAS_QUIET_NAN__
> + e = (v1sf){__builtin_nanf("")};
> + f = e;
> + /* Test NaNs */
> + r = f1(a,b,c,d,e, f);
> + r1 = f2(a[0], b[0], c[0], d[0], e[0], f[0]);
> + if (r[0] != r1)
> + __builtin_abort();
> +#endif
> +}
> diff --git a/gcc/testsuite/g++.dg/tree-ssa/pr111150.C b/gcc/testsuite/g++.dg/tree-ssa/pr111150.C
> index ac5d3ef15d8..82af8f96878 100644
> --- a/gcc/testsuite/g++.dg/tree-ssa/pr111150.C
> +++ b/gcc/testsuite/g++.dg/tree-ssa/pr111150.C
> @@ -32,3 +32,13 @@ v4si f4_(v4si a, v4si b, v4si c, v4si d, v4si e, v4si f) {
>
> /* For each testcase, should produce only one VEC_COND_EXPR for X^Y. */
> /* { dg-final { scan-tree-dump-times " VEC_COND_EXPR " 4 "forwprop1" } } */
> +/* 2 IOR, one each for f1 and f2.
> + 2 AND, one each for f3 and f4. */
> +/* { dg-final { scan-tree-dump-times " & " 2 "forwprop1" } } */
> +/* { dg-final { scan-tree-dump-times " \\| " 2 "forwprop1" } } */
> +/* { dg-final { scan-tree-dump-times " \\^ " 4 "forwprop1" } } */
> +/* 8 eq comparisons from each of `a == b`/`c == d`.
> + 2 more to check that `e == f`
> + 2 ne comparisons to check that `e != f`. */
> +/* { dg-final { scan-tree-dump-times " == " 10 "forwprop1" } } */
> +/* { dg-final { scan-tree-dump-times " != " 2 "forwprop1" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr111150-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr111150-1.c
> index 6f4b21ac6bc..1970f7fe496 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/pr111150-1.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr111150-1.c
> @@ -69,4 +69,13 @@ _Bool f4_(int a, int b, int c, int d, int e, int f) {
>
> /* Should generate one bit_xor_expr for each testcase. */
> /* { dg-final { scan-tree-dump-not "cond_expr, " "forwprop1" } } */
> +/* 2 IOR, one each for f1 and f2.
> + 2 AND, one each for f3 and f4. */
> +/* { dg-final { scan-tree-dump-times "bit_ior_expr, " 2 "forwprop1" } } */
> +/* { dg-final { scan-tree-dump-times "bit_and_expr, " 2 "forwprop1" } } */
> /* { dg-final { scan-tree-dump-times "bit_xor_expr, " 4 "forwprop1" } } */
> +/* 8 eq comparisons from each of `a == b`/`c == d`.
> + 2 more to check that `e == f`
> + 2 ne comparisons to check that `e != f`. */
> +/* { dg-final { scan-tree-dump-times "<ne_expr, " 2 "forwprop1" } } */
> +/* { dg-final { scan-tree-dump-times "<eq_expr, " 10 "forwprop1" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr111150.c b/gcc/testsuite/gcc.dg/tree-ssa/pr111150.c
> index 568ae9e44b3..6370be8cfd2 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/pr111150.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr111150.c
> @@ -20,3 +20,4 @@ v4si f2_(v4si a, v4si b, v4si c, v4si d) {
>
> /* For each testcase, should produce only one VEC_COND_EXPR for X^Y. */
> /* { dg-final { scan-tree-dump-times " VEC_COND_EXPR " 2 "forwprop1" } } */
> +/* { dg-final { scan-tree-dump-times " == " 4 "forwprop1" } } */
> --
> 2.43.0
>
@@ -5632,21 +5632,28 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(vec_cond (bit_and (bit_not @0) @1) @2 @3)))
#endif
-/* (a ? x : y) != (b ? x : y) --> (a^b) ? TRUE : FALSE */
-/* (a ? x : y) == (b ? x : y) --> (a^b) ? FALSE : TRUE */
-/* (a ? x : y) != (b ? y : x) --> (a^b) ? FALSE : TRUE */
-/* (a ? x : y) == (b ? y : x) --> (a^b) ? TRUE : FALSE */
+/* (a ? x : y) != (b ? x : y) --> (a^b & (x != y)) ? TRUE : FALSE */
+/* (a ? x : y) == (b ? x : y) --> (a^b & (x != y)) ? FALSE : TRUE */
+/* (a ? x : y) != (b ? y : x) --> (a^b | (x == y)) ? FALSE : TRUE */
+/* (a ? x : y) == (b ? y : x) --> (a^b | (x == y)) ? TRUE : FALSE */
+/* These are only valid if x and y don't have NaNs. */
(for cnd (cond vec_cond)
(for eqne (eq ne)
(simplify
(eqne:c (cnd @0 @1 @2) (cnd @3 @1 @2))
- (if (types_match (TREE_TYPE (@0), TREE_TYPE (@3)))
- (cnd (bit_xor @0 @3) { constant_boolean_node (eqne == NE_EXPR, type); }
+ (if (!HONOR_NANS (@1)
+ && types_match (TREE_TYPE (@0), TREE_TYPE (@3))
+ && types_match (type, TREE_TYPE (@0)))
+ (cnd (bit_and (bit_xor @0 @3) (ne:type @1 @2))
+ { constant_boolean_node (eqne == NE_EXPR, type); }
{ constant_boolean_node (eqne != NE_EXPR, type); })))
(simplify
(eqne:c (cnd @0 @1 @2) (cnd @3 @2 @1))
- (if (types_match (TREE_TYPE (@0), TREE_TYPE (@3)))
- (cnd (bit_xor @0 @3) { constant_boolean_node (eqne != NE_EXPR, type); }
+ (if (!HONOR_NANS (@1)
+ && types_match (TREE_TYPE (@0), TREE_TYPE (@3))
+ && types_match (type, TREE_TYPE (@0)))
+ (cnd (bit_ior (bit_xor @0 @3) (eq:type @1 @2))
+ { constant_boolean_node (eqne != NE_EXPR, type); }
{ constant_boolean_node (eqne == NE_EXPR, type); })))))
/* Canonicalize mask ? { 0, ... } : { -1, ...} to ~mask if the mask
new file mode 100644
@@ -0,0 +1,32 @@
+// { dg-do run }
+// PR tree-optimization/116120
+
+// The optimization for `(a ? x : y) != (b ? x : y)`
+// missed that x and y could be the same value.
+
+typedef int v4si __attribute((__vector_size__(1 * sizeof(int))));
+v4si f1(v4si a, v4si b, v4si c, v4si d, v4si e, v4si f) {
+ v4si X = a == b ? e : f;
+ v4si Y = c == d ? e : f;
+ return (X != Y); // ~(X == Y ? -1 : 0) (x ^ Y)
+}
+
+int f2(int a, int b, int c, int d, int e, int f) {
+ int X = a == b ? e : f;
+ int Y = c == d ? e : f;
+ return (X != Y) ? -1 : 0; // ~(X == Y ? -1 : 0) (x ^ Y)
+}
+
+int main()
+{
+ v4si a = {0};
+ v4si b = {0}; // a == b, true
+ v4si c = {2};
+ v4si d = {3}; // c == b, false
+ v4si e = {0};
+ v4si f = e;
+ v4si r = f1(a,b,c,d,e, f);
+ int r1 = f2(a[0], b[0], c[0], d[0], e[0], f[0]);
+ if (r[0] != r1)
+ __builtin_abort();
+}
new file mode 100644
@@ -0,0 +1,53 @@
+// { dg-do run }
+// PR tree-optimization/116120
+
+// The optimization for `(a ? x : y) == (b ? x : y)`
+// missed that x and y could be the same value
+// This can't be done if x and y support NaNs since `NaN == NaN` is always false
+// And dominates the whole expression rather than supporting it.
+
+typedef int v1si __attribute((__vector_size__(1 * sizeof(int))));
+typedef float v1sf __attribute((__vector_size__(1 * sizeof(float))));
+
+v1si f1(v1si a, v1si b, v1si c, v1si d, v1sf e, v1sf f) __attribute__((noinline));
+v1si f1(v1si a, v1si b, v1si c, v1si d, v1sf e, v1sf f) {
+ v1sf X = a == b ? e : f;
+ v1sf Y = c == d ? f : e;
+ return (X == Y); // ~(X == Y ? -1 : 0) (x ^ Y)
+}
+
+int f2(int a, int b, int c, int d, float e, float f) __attribute__((noinline));
+int f2(int a, int b, int c, int d, float e, float f) {
+ float X = a == b ? e : f;
+ float Y = c == d ? f : e;
+ return (X == Y) ? -1 : 0; // ~(X == Y ? -1 : 0) (x ^ Y)
+}
+
+int main()
+{
+ v1si a = {0};
+ v1si b = {0}; // a == b, true
+ v1si c = {2};
+ v1si d = {3}; // c == b, false
+ v1sf e;
+ v1sf f;
+
+ /* Test signed 0s. */
+ e = (v1sf){0.0};
+ f = -e;
+ v1si r = f1(a,b,c,d,e, f);
+ int r1 = f2(a[0], b[0], c[0], d[0], e[0], f[0]);
+ if (r[0] != r1)
+ __builtin_abort();
+
+ /* Test NaNs */
+#if __FLT_HAS_QUIET_NAN__
+ e = (v1sf){__builtin_nanf("")};
+ f = e;
+ /* Test NaNs */
+ r = f1(a,b,c,d,e, f);
+ r1 = f2(a[0], b[0], c[0], d[0], e[0], f[0]);
+ if (r[0] != r1)
+ __builtin_abort();
+#endif
+}
@@ -32,3 +32,13 @@ v4si f4_(v4si a, v4si b, v4si c, v4si d, v4si e, v4si f) {
/* For each testcase, should produce only one VEC_COND_EXPR for X^Y. */
/* { dg-final { scan-tree-dump-times " VEC_COND_EXPR " 4 "forwprop1" } } */
+/* 2 IOR, one each for f1 and f2.
+ 2 AND, one each for f3 and f4. */
+/* { dg-final { scan-tree-dump-times " & " 2 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-times " \\| " 2 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-times " \\^ " 4 "forwprop1" } } */
+/* 8 eq comparisons from each of `a == b`/`c == d`.
+ 2 more to check that `e == f`
+ 2 ne comparisons to check that `e != f`. */
+/* { dg-final { scan-tree-dump-times " == " 10 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-times " != " 2 "forwprop1" } } */
@@ -69,4 +69,13 @@ _Bool f4_(int a, int b, int c, int d, int e, int f) {
/* Should generate one bit_xor_expr for each testcase. */
/* { dg-final { scan-tree-dump-not "cond_expr, " "forwprop1" } } */
+/* 2 IOR, one each for f1 and f2.
+ 2 AND, one each for f3 and f4. */
+/* { dg-final { scan-tree-dump-times "bit_ior_expr, " 2 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-times "bit_and_expr, " 2 "forwprop1" } } */
/* { dg-final { scan-tree-dump-times "bit_xor_expr, " 4 "forwprop1" } } */
+/* 8 eq comparisons from each of `a == b`/`c == d`.
+ 2 more to check that `e == f`
+ 2 ne comparisons to check that `e != f`. */
+/* { dg-final { scan-tree-dump-times "<ne_expr, " 2 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-times "<eq_expr, " 10 "forwprop1" } } */
@@ -20,3 +20,4 @@ v4si f2_(v4si a, v4si b, v4si c, v4si d) {
/* For each testcase, should produce only one VEC_COND_EXPR for X^Y. */
/* { dg-final { scan-tree-dump-times " VEC_COND_EXPR " 2 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-times " == " 4 "forwprop1" } } */