Am Mittwoch, den 22.09.2021, 17:18 -0400 schrieb Jason Merrill: > On 9/5/21 15:14, Uecker, Martin wrote: > > Here is the third version of the patch. This also > > fixes the index zero case. Thus, this should be > > a complete fix for 91038 and should fix all cases > > also supported by clang. Still not working is > > returning a struct of variable size from a > > statement expression (29970) when the size depends > > on computations inside the statement expression. > > > > Bootstrapped and regression tested > > on x86-64 for all languages. > > > > Martin > > > > > > > > > > Fix ICE when mixing VLAs and statement expressions [PR91038] > > > > When returning VM-types from statement expressions, this can > > lead to an ICE when declarations from the statement expression > > are referred to later. Most of these issues can be addressed by > > gimplifying the base expression earlier in gimplify_compound_lval. > > Another issue is fixed by not reording some size-related expressions > > during folding. This fixes PR91038 and some of the test cases > > from PR29970 (structs with VLA members need further work). > > > > > > 2021-08-01 Martin Uecker <muec...@gwdg.de> > > > > gcc/ > > PR c/91038 > > PR c/29970 > > * gimplify.c (gimplify_var_or_parm_decl): Update comment. > > (gimplify_compound_lval): Gimplify base expression first. > > (gimplify_target_expr): Do not gimplify size expression. > > * fold-const.c (fold_binary_loc): Do not reorder SAVE_EXPR > > in pointer arithmetic for variably modified types. > > > > gcc/testsuite/ > > PR c/91038 > > PR c/29970 > > * gcc.dg/vla-stexp-3.c: New test. > > * gcc.dg/vla-stexp-4.c: New test. > > * gcc.dg/vla-stexp-5.c: New test. > > * gcc.dg/vla-stexp-6.c: New test. > > * gcc.dg/vla-stexp-7.c: New test. > > * gcc.dg/vla-stexp-8.c: New test. > > * gcc.dg/vla-stexp-9.c: New test. > > > > > > diff --git a/gcc/fold-const.c b/gcc/fold-const.c > > index ff23f12f33c..1e6f50692b5 100644 > > --- a/gcc/fold-const.c > > +++ b/gcc/fold-const.c > > @@ -10854,7 +10854,15 @@ fold_binary_loc (location_t loc, enum tree_code > > code, tree type, > > return build2_loc (loc, COMPOUND_EXPR, type, TREE_OPERAND (arg0, 0), > > tem); > > } > > - if (TREE_CODE (arg1) == COMPOUND_EXPR) > > + /* This interleaves execution of the two sub-expressions > > + which is allowed in C. For pointer arithmetic when the > > + the pointer has a variably modified type, the right expression > > + might have a SAVE_EXPR which depends on the left expr, so > > + do not fold in this case. */ > > + if (TREE_CODE (arg1) == COMPOUND_EXPR > > + && !(code == POINTER_PLUS_EXPR > > + && TREE_CODE (TREE_OPERAND (arg1, 0)) == SAVE_EXPR) > > + && variably_modified_type_p (type, NULL_TREE)) > > This seems pretty fragile. If the problem is that the SAVE_EXPR depends > on a statement-expr on the LHS, can't that happen with expressions other > than POINTER_PLUS_EXPR?
I intentionally limited the change to this specific case to avoid accidentally breaking or pessimizing anything else. I did not notice any other cases that need fixing. It is of course possible that I have missed some... > > Maybe we should include the statement-expr in the SAVE_EXPR? I am not really sure how to implement this. Maybe we could apply this patch first (because I have to work around this bug in a couple of projects which is a bit annoying)? I am happy to implement an alternative later if there is a better way (which I can understand). Martin > > { > > tem = fold_build2_loc (loc, code, type, op0, > > fold_convert_loc (loc, TREE_TYPE (op1), > > diff --git a/gcc/gimplify.c b/gcc/gimplify.c > > index 99d1c7fcce4..8ee205f593c 100644 > > --- a/gcc/gimplify.c > > +++ b/gcc/gimplify.c > > @@ -2840,7 +2840,10 @@ gimplify_var_or_parm_decl (tree *expr_p) > > declaration, for which we've already issued an error. It would > > be really nice if the front end wouldn't leak these at all. > > Currently the only known culprit is C++ destructors, as seen > > - in g++.old-deja/g++.jason/binding.C. */ > > + in g++.old-deja/g++.jason/binding.C. > > + Another possible culpit are size expressions for variably modified > > + types which are lost in the FE or not gimplified correctly. > > + */ > > if (VAR_P (decl) > > && !DECL_SEEN_IN_BIND_EXPR_P (decl) > > && !TREE_STATIC (decl) && !DECL_EXTERNAL (decl) > > @@ -2985,16 +2988,22 @@ gimplify_compound_lval (tree *expr_p, gimple_seq > > *pre_p, gimple_seq > > *post_p, > > expression until we deal with any variable bounds, sizes, or > > positions in order to deal with PLACEHOLDER_EXPRs. > > > > - So we do this in three steps. First we deal with the annotations > > - for any variables in the components, then we gimplify the base, > > - then we gimplify any indices, from left to right. */ > > + The base expression may contain a statement expression that > > + has declarations used in size expressions, so has to be > > + gimplified before gimplifying the size expressions. > > + > > + So we do this in three steps. First we deal with variable > > + bounds, sizes, and positions, then we gimplify the base, > > + then we deal with the annotations for any variables in the > > + components and any indices, from left to right. */ > > + > > for (i = expr_stack.length () - 1; i >= 0; i--) > > { > > tree t = expr_stack[i]; > > > > if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) > > { > > - /* Gimplify the low bound and element type size and put them into > > + /* Deal with the low bound and element type size and put them into > > the ARRAY_REF. If these values are set, they have already been > > gimplified. */ > > if (TREE_OPERAND (t, 2) == NULL_TREE) > > @@ -3003,18 +3012,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq > > *pre_p, gimple_seq > > *post_p, > > if (!is_gimple_min_invariant (low)) > > { > > TREE_OPERAND (t, 2) = low; > > - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, > > - post_p, is_gimple_reg, > > - fb_rvalue); > > - ret = MIN (ret, tret); > > } > > } > > - else > > - { > > - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, > > - is_gimple_reg, fb_rvalue); > > - ret = MIN (ret, tret); > > - } > > > > if (TREE_OPERAND (t, 3) == NULL_TREE) > > { > > @@ -3031,18 +3030,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq > > *pre_p, gimple_seq > > *post_p, > > elmt_size, factor); > > > > TREE_OPERAND (t, 3) = elmt_size; > > - tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, > > - post_p, is_gimple_reg, > > - fb_rvalue); > > - ret = MIN (ret, tret); > > } > > } > > - else > > - { > > - tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, post_p, > > - is_gimple_reg, fb_rvalue); > > - ret = MIN (ret, tret); > > - } > > } > > else if (TREE_CODE (t) == COMPONENT_REF) > > { > > @@ -3062,18 +3051,8 @@ gimplify_compound_lval (tree *expr_p, gimple_seq > > *pre_p, gimple_seq > > *post_p, > > offset, factor); > > > > TREE_OPERAND (t, 2) = offset; > > - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, > > - post_p, is_gimple_reg, > > - fb_rvalue); > > - ret = MIN (ret, tret); > > } > > } > > - else > > - { > > - tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, > > - is_gimple_reg, fb_rvalue); > > - ret = MIN (ret, tret); > > - } > > } > > } > > > > @@ -3084,21 +3063,34 @@ gimplify_compound_lval (tree *expr_p, gimple_seq > > *pre_p, gimple_seq > > *post_p, > > fallback | fb_lvalue); > > ret = MIN (ret, tret); > > > > - /* And finally, the indices and operands of ARRAY_REF. During this > > - loop we also remove any useless conversions. */ > > + /* Step 3: gimplify size expressions and the indices and operands of > > + ARRAY_REF. During this loop we also remove any useless conversions. > > */ > > + > > for (; expr_stack.length () > 0; ) > > { > > tree t = expr_stack.pop (); > > > > if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) > > { > > + /* Gimplify the low bound and element type size. */ > > + tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, > > + is_gimple_reg, fb_rvalue); > > + ret = MIN (ret, tret); > > + > > + tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p, post_p, > > + is_gimple_reg, fb_rvalue); > > + ret = MIN (ret, tret); > > + > > /* Gimplify the dimension. */ > > - if (!is_gimple_min_invariant (TREE_OPERAND (t, 1))) > > - { > > - tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p, > > - is_gimple_val, fb_rvalue); > > - ret = MIN (ret, tret); > > - } > > + tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p, > > + is_gimple_val, fb_rvalue); > > + ret = MIN (ret, tret); > > + } > > + else if (TREE_CODE (t) == COMPONENT_REF) > > + { > > + tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p, > > + is_gimple_reg, fb_rvalue); > > + ret = MIN (ret, tret); > > } > > > > STRIP_USELESS_TYPE_CONVERSION (TREE_OPERAND (t, 0)); > > @@ -6766,8 +6758,8 @@ gimplify_target_expr (tree *expr_p, gimple_seq > > *pre_p, gimple_seq *post_p) > > to the temps list. Handle also variable length TARGET_EXPRs. */ > > if (!poly_int_tree_p (DECL_SIZE (temp))) > > { > > - if (!TYPE_SIZES_GIMPLIFIED (TREE_TYPE (temp))) > > - gimplify_type_sizes (TREE_TYPE (temp), pre_p); > > + /* FIXME: this is correct only when the size of the type does > > + not depend on expressions evaluated in init. */ > > gimplify_vla_decl (temp, pre_p); > > } > > else > > diff --git a/gcc/testsuite/gcc.dg/vla-stexp-3.c > > b/gcc/testsuite/gcc.dg/vla-stexp-3.c > > new file mode 100644 > > index 00000000000..e663de1cd72 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.dg/vla-stexp-3.c > > @@ -0,0 +1,11 @@ > > +/* PR91038 */ > > +/* { dg-do compile } */ > > +/* { dg-options "" } */ > > + > > + > > +void bar(void) > > +{ > > + ({ int N = 2; int (*x)[9][N] = 0; x; })[1]; > > + ({ int N = 2; int (*x)[9][N] = 0; x; })[0]; // should not ice > > +} > > + > > diff --git a/gcc/testsuite/gcc.dg/vla-stexp-4.c > > b/gcc/testsuite/gcc.dg/vla-stexp-4.c > > new file mode 100644 > > index 00000000000..612b5a802fc > > --- /dev/null > > +++ b/gcc/testsuite/gcc.dg/vla-stexp-4.c > > @@ -0,0 +1,94 @@ > > +/* PR29970, PR91038 */ > > +/* { dg-do run } */ > > +/* { dg-options "-O0 -Wunused-variable" } */ > > + > > +int foo3b(void) // should not return 0 > > +{ > > + int n = 0; > > + return sizeof *({ n = 10; int x[n]; &x; }); > > +} > > + > > +int foo4(void) // should not ICE > > +{ > > + return (*({ > > + int n = 20; > > + char (*x)[n][n] = __builtin_malloc(n * n); > > + (*x)[12][1] = 1; > > + x; > > + }))[12][1]; > > +} > > + > > +int foo5(void) // should return 1, returns 0 > > +{ > > + int n = 0; > > + return (*({ > > + n = 20; > > + char (*x)[n][n] = __builtin_malloc(n * n); > > + (*x)[12][1] = 1; > > + (*x)[0][1] = 0; > > + x; > > + }))[12][1]; > > +} > > + > > +int foo5c(void) // should return 400 > > +{ > > + int n = 0; > > + return sizeof(*({ > > + n = 20; > > + char (*x)[n][n] = __builtin_malloc(n * n); > > + (*x)[12][1] = 1; > > + (*x)[0][1] = 0; > > + x; > > + })); > > +} > > + > > +int foo5b(void) // should return 1, returns 0 > > +{ > > + int n = 0; /* { dg-warning "unused variable" } */ > > + return (*({ > > + int n = 20; > > + char (*x)[n][n] = __builtin_malloc(n * n); > > + (*x)[12][1] = 1; > > + (*x)[0][1] = 0; > > + x; > > + }))[12][1]; > > +} > > + > > +int foo5a(void) // should return 1, returns 0 > > +{ > > + return (*({ > > + int n = 20; > > + char (*x)[n][n] = __builtin_malloc(n * n); > > + (*x)[12][1] = 1; > > + (*x)[0][1] = 0; > > + x; > > + }))[12][1]; > > +} > > + > > + > > + > > + > > +int main() > > +{ > > + if (sizeof(int[10]) != foo3b()) > > + __builtin_abort(); > > + > > + if (1 != foo4()) > > + __builtin_abort(); > > + > > + if (400 != foo5c()) > > + __builtin_abort(); > > + > > + if (1 != foo5a()) > > + __builtin_abort(); > > + > > + if (1 != foo5b()) // -O0 > > + __builtin_abort(); > > + > > + if (1 != foo5()) > > + __builtin_abort(); > > + > > + return 0; > > +} > > + > > + > > diff --git a/gcc/testsuite/gcc.dg/vla-stexp-5.c > > b/gcc/testsuite/gcc.dg/vla-stexp-5.c > > new file mode 100644 > > index 00000000000..d6a7f2b34b8 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.dg/vla-stexp-5.c > > @@ -0,0 +1,30 @@ > > +/* PR29970 */ > > +/* { dg-do run } */ > > +/* { dg-options "-Wunused-variable" } */ > > + > > + > > + > > + > > +int foo2a(void) // should not ICE > > +{ > > + return ({ int n = 20; struct { int x[n];} x; x.x[12] = 1; > > sizeof(x); }); > > +} > > + > > + > > +int foo2b(void) // should not ICE > > +{ > > + return sizeof *({ int n = 20; struct { int x[n];} x; x.x[12] = 1; > > &x; }); > > +} > > + > > +int main() > > +{ > > + if (sizeof(struct { int x[20]; }) != foo2a()) > > + __builtin_abort(); > > + > > + if (sizeof(struct { int x[20]; }) != foo2b()) > > + __builtin_abort(); > > + > > + return 0; > > +} > > + > > + > > diff --git a/gcc/testsuite/gcc.dg/vla-stexp-6.c > > b/gcc/testsuite/gcc.dg/vla-stexp-6.c > > new file mode 100644 > > index 00000000000..3d96d38898b > > --- /dev/null > > +++ b/gcc/testsuite/gcc.dg/vla-stexp-6.c > > @@ -0,0 +1,94 @@ > > +/* PR29970, PR91038 */ > > +/* { dg-do run } */ > > +/* { dg-options "-O2 -Wunused-variable" } */ > > + > > +int foo3b(void) // should not return 0 > > +{ > > + int n = 0; > > + return sizeof *({ n = 10; int x[n]; &x; }); > > +} > > + > > +int foo4(void) // should not ICE > > +{ > > + return (*({ > > + int n = 20; > > + char (*x)[n][n] = __builtin_malloc(n * n); > > + (*x)[12][1] = 1; > > + x; > > + }))[12][1]; > > +} > > + > > +int foo5(void) // should return 1, returns 0 > > +{ > > + int n = 0; > > + return (*({ > > + n = 20; > > + char (*x)[n][n] = __builtin_malloc(n * n); > > + (*x)[12][1] = 1; > > + (*x)[0][1] = 0; > > + x; > > + }))[12][1]; > > +} > > + > > +int foo5c(void) // should return 400 > > +{ > > + int n = 0; > > + return sizeof(*({ > > + n = 20; > > + char (*x)[n][n] = __builtin_malloc(n * n); > > + (*x)[12][1] = 1; > > + (*x)[0][1] = 0; > > + x; > > + })); > > +} > > + > > +int foo5b(void) // should return 1, returns 0 > > +{ > > + int n = 0; /* { dg-warning "unused variable" } */ > > + return (*({ > > + int n = 20; > > + char (*x)[n][n] = __builtin_malloc(n * n); > > + (*x)[12][1] = 1; > > + (*x)[0][1] = 0; > > + x; > > + }))[12][1]; > > +} > > + > > +int foo5a(void) // should return 1, returns 0 > > +{ > > + return (*({ > > + int n = 20; > > + char (*x)[n][n] = __builtin_malloc(n * n); > > + (*x)[12][1] = 1; > > + (*x)[0][1] = 0; > > + x; > > + }))[12][1]; > > +} > > + > > + > > + > > + > > +int main() > > +{ > > + if (sizeof(int[10]) != foo3b()) > > + __builtin_abort(); > > + > > + if (1 != foo4()) > > + __builtin_abort(); > > + > > + if (400 != foo5c()) > > + __builtin_abort(); > > + > > + if (1 != foo5a()) > > + __builtin_abort(); > > + > > + if (1 != foo5b()) // -O0 > > + __builtin_abort(); > > + > > + if (1 != foo5()) > > + __builtin_abort(); > > + > > + return 0; > > +} > > + > > + > > diff --git a/gcc/testsuite/gcc.dg/vla-stexp-7.c > > b/gcc/testsuite/gcc.dg/vla-stexp-7.c > > new file mode 100644 > > index 00000000000..3091b9184c2 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.dg/vla-stexp-7.c > > @@ -0,0 +1,44 @@ > > +/* PR91038 */ > > +/* { dg-do run } */ > > +/* { dg-options "-O2 -Wunused-variable" } */ > > + > > + > > +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) > > + > > +struct lbm { > > + > > + int D; > > + const int* DQ; > > + > > +} D2Q9 = { 2, > > + (const int*)&(const int[9][2]){ > > + { 0, 0 }, > > + { 1, 0 }, { 0, 1 }, { -1, 0 }, { 0, -1 }, > > + { 1, 1 }, { -1, 1 }, { -1, -1 }, { 1, -1 }, > > + } > > +}; > > + > > +void zouhe_left(void) > > +{ > > + __auto_type xx = (*({ int N = 2; struct lbm __x = D2Q9; ((const > > int(*)[9][N])__x.DQ); })); > > + > > + if (1 != xx[1][0]) > > + __builtin_abort(); > > + > > + if (2 != ARRAY_SIZE(xx[1])) > > + __builtin_abort(); > > + > > + if (1 != (*({ int N = 2; struct lbm __x = D2Q9; ((const > > int(*)[9][N])__x.DQ); }))[1][0]) > > + __builtin_abort(); > > + > > + if (2 != ARRAY_SIZE(*({ int N = 2; struct lbm __x = D2Q9; ((const > > int(*)[9][N])__x.DQ); > > })[1])) > > + __builtin_abort(); > > +} > > + > > +int main() > > +{ > > + zouhe_left(); > > + return 0; > > +} > > + > > + > > diff --git a/gcc/testsuite/gcc.dg/vla-stexp-8.c > > b/gcc/testsuite/gcc.dg/vla-stexp-8.c > > new file mode 100644 > > index 00000000000..5b475eb6cf2 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.dg/vla-stexp-8.c > > @@ -0,0 +1,47 @@ > > +/* PR29970, PR91038 */ > > +/* { dg-do compile } */ > > +/* { dg-options "-O2 -Wunused-variable" } */ > > + > > + > > +int foo0(void) > > +{ > > + int c = *(*(*({ int n = 10; int (*x)[n][n] = __builtin_malloc(sizeof > > *x); x; }) + 5) + 5); > > + return c; > > +} > > + > > +int foo1(void) > > +{ > > + int c = *(5 + *(5 + *({ int n = 10; int (*x)[n][n] = > > __builtin_malloc(sizeof *x); x; }))); > > + return c; > > +} > > + > > +int bar2(void) > > +{ > > + int c = (*({ int n = 10; struct { int y[n]; int z; }* x = > > __builtin_malloc(sizeof *x); x; > > })).z; > > + return c; > > +} > > + > > +int bar3(void) > > +{ > > + int n = 2; /* { dg-warning "unused variable" } */ > > + int c = (*({ int n = 3; /* { dg-warning "unused variable" } */ > > + ({ int n = 10; int (*x)[n][n] = __builtin_malloc(sizeof *x); x; > > }); }))[5][5]; > > + return c; > > +} > > + > > +int bar3b(void) > > +{ > > + int n = 2; /* { dg-warning "unused variable" } */ > > + int c = (*({ int n = 3; /* { dg-warning "unused variable" } */ > > + ({ int n = 10; int (*x)[n][n] = __builtin_malloc(sizeof *x); x; > > }); }))[0][0]; > > + return c; > > +} > > + > > +int bar4(void) > > +{ > > + int n = 2; /* { dg-warning "unused variable" } */ > > + int c = *(5 + *( 5 + *({ int n = 3; /* { dg-warning "unused > > variable" } */ > > + ({ int n = 10; int (*x)[n][n] = __builtin_malloc(sizeof *x); x; > > }); }))); > > + return c; > > +} > > + > > diff --git a/gcc/testsuite/gcc.dg/vla-stexp-9.c > > b/gcc/testsuite/gcc.dg/vla-stexp-9.c > > new file mode 100644 > > index 00000000000..3593a790785 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.dg/vla-stexp-9.c > > @@ -0,0 +1,53 @@ > > +/* PR91038 */ > > +/* { dg-do run } */ > > +/* { dg-options "-O2 -Wunused-variable" } */ > > + > > + > > + > > +void foo(void) > > +{ > > + if (2 * sizeof(int) != sizeof((*({ int N = 2; int (*x)[9][N] = 0; x; > > })[1]))) > > + __builtin_abort(); > > +} > > + > > +void bar(void) > > +{ > > + if (2 * sizeof(int) != sizeof((*({ int N = 2; int (*x)[9][N] = 0; x; > > })[0]))) > > + __builtin_abort(); > > +} > > + > > +void bar0(void) > > +{ > > + if (2 * 9 * sizeof(int) != sizeof((*({ int N = 2; int (*x)[9][N] = 0; > > x; })))) > > + __builtin_abort(); > > +} > > + > > +void bar11(void) > > +{ > > + sizeof(*((*({ int N = 2; int (*x)[9][N] = 0; x; }) + 0))); > > +} > > + > > +void bar12(void) > > +{ > > + if (2 * sizeof(int) != sizeof(*((*({ int N = 2; int (*x)[9][N] = 0; x; > > }) )))) > > + __builtin_abort(); > > +} > > + > > +void bar1(void) > > +{ > > + if (2 * sizeof(int) != sizeof(*((*({ int N = 2; int (*x)[9][N] = 0; x; > > }) + 0)))) > > + __builtin_abort(); > > +} > > + > > + > > + > > + > > +int main() > > +{ > > + foo(); > > + bar0(); > > + bar12(); > > + bar1(); > > + bar(); > > +} > > + > >