[gcc r12-7934] tree-optimization/105109 - bogus uninit diagnostic with _Complex

[gcc r12-7934] tree-optimization/105109 - bogus uninit diagnostic with _Complex

[Richard Biener]

https://gcc.gnu.org/g:97ad0b831386e56ecb125a25fff00b2cb0b1a2b9

commit r12-7934-g97ad0b831386e56ecb125a25fff00b2cb0b1a2b9
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Mar 31 09:21:27 2022 +0200

    tree-optimization/105109 - bogus uninit diagnostic with _Complex
    
    When update_address_taken rewrites a _Complex into SSA it changes
    stores to real/imaginary parts to loads of the other component and
    a COMPLEX_EXPR.  That matches what gimplification does but it misses
    suppression of diagnostics for the load of the other component.
    The following patch adds that, syncing up gimplification and
    update_address_taken behavior.
    
    2022-03-31  Richard Biener  <rguenther@suse.de>
    
            PR tree-optimization/105109
            * tree-ssa.cc (execute_update_addresses_taken): Suppress
            diagnostics on the load of the other complex component.
    
            * gcc.dg/uninit-pr105109.c: New testcase.

Diff:
---
 gcc/testsuite/gcc.dg/uninit-pr105109.c | 15 +++++++++++++++
 gcc/tree-ssa.cc                        |  1 +
 2 files changed, 16 insertions(+)

diff --git a/gcc/testsuite/gcc.dg/uninit-pr105109.c b/gcc/testsuite/gcc.dg/uninit-pr105109.c
new file mode 100644
index 00000000000..001003ca261
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/uninit-pr105109.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized" } */
+
+static void foo(int dim,float _Complex f0[])
+{
+  int d;
+  f0[0] -= 3.14;  /* { dg-bogus "uninitialized" } */
+  for (d = 0; d < dim; ++d) f0[0] += 3.14;
+}
+void bar(int dim, const float _Complex u_t[], float _Complex f0[])
+{
+  float _Complex exp[1] = {0.};
+  foo(dim, exp);
+  f0[0] = u_t[0] - exp[0];
+}
diff --git a/gcc/tree-ssa.cc b/gcc/tree-ssa.cc
index 6dcb3142869..a362a0a9ea6 100644
--- a/gcc/tree-ssa.cc
+++ b/gcc/tree-ssa.cc
@@ -1905,6 +1905,7 @@ execute_update_addresses_taken (void)
 					? REALPART_EXPR : IMAGPART_EXPR,
 					TREE_TYPE (other),
 					TREE_OPERAND (lhs, 0));
+		    suppress_warning (lrhs);
 		    gimple *load = gimple_build_assign (other, lrhs);
 		    location_t loc = gimple_location (stmt);
 		    gimple_set_location (load, loc);