From a94dcac59ee4c99b523ae593cb1c0ad43d4a110b Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Fri, 28 Apr 2023 08:40:07 +0200
Subject: [PATCH] ipa/109652 - ICE in modification phase of IPA SRA

There's another questionable IL transform by IPA SRA, replacing
foo (p_1(D)->x) with foo (VIEW_CONVERT <union type> (ISRA.PARM.1))
where ISRA.PARM.1 is a register.  Conversion of a register to
an aggregate type is questionable but not entirely unreasonable
and not within the set of IL I am rejecting when fixing PR109644.

The following lets this slip through in IPA SRA transform by
restricting re-gimplification to the case of register type
results.  To not break the previous testcase again we need to
optimize the BIT_FIELD_REF <VIEW_CONVERT <...>, ...> case
to elide the conversion.

	PR ipa/109652
	* ipa-param-manipulation.cc
	(ipa_param_body_adjustments::modify_expression): Allow
	conversion of a register to a non-register type.  Elide
	conversions inside BIT_FIELD_REFs.

	* gcc.dg/torture/pr109652.c: New testcase.
---
 gcc/ipa-param-manipulation.cc           |  7 +++--
 gcc/testsuite/gcc.dg/torture/pr109652.c | 40 +++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr109652.c

diff --git a/gcc/ipa-param-manipulation.cc b/gcc/ipa-param-manipulation.cc
index 33dcab9c33c..a286af7f5d9 100644
--- a/gcc/ipa-param-manipulation.cc
+++ b/gcc/ipa-param-manipulation.cc
@@ -1836,9 +1836,11 @@ ipa_param_body_adjustments::modify_expression (tree *expr_p, bool convert,
       || TREE_CODE (expr) == IMAGPART_EXPR
       || TREE_CODE (expr) == REALPART_EXPR)
     {
+      /* For a BIT_FIELD_REF do not bother to VIEW_CONVERT the base,
+	 instead reference the replacement directly.  */
+      convert = TREE_CODE (expr) != BIT_FIELD_REF;
       expr_p = &TREE_OPERAND (expr, 0);
       expr = *expr_p;
-      convert = true;
     }
 
   ipa_param_body_replacement *pbr = get_expr_replacement (expr, false);
@@ -1861,7 +1863,8 @@ ipa_param_body_adjustments::modify_expression (tree *expr_p, bool convert,
       gcc_checking_assert (tree_to_shwi (TYPE_SIZE (TREE_TYPE (expr)))
 			   == tree_to_shwi (TYPE_SIZE (TREE_TYPE (repl))));
       tree vce = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (expr), repl);
-      if (is_gimple_reg (repl))
+      if (is_gimple_reg (repl)
+	  && is_gimple_reg_type (TREE_TYPE (expr)))
 	{
 	  gcc_assert (extra_stmts);
 	  vce = force_gimple_operand (vce, extra_stmts, true, NULL_TREE);
diff --git a/gcc/testsuite/gcc.dg/torture/pr109652.c b/gcc/testsuite/gcc.dg/torture/pr109652.c
new file mode 100644
index 00000000000..8a6524d2212
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr109652.c
@@ -0,0 +1,40 @@
+/* { dg-do compile } */
+
+typedef int UInt;
+UInt skeletal_RI5_instr;
+__attribute__((__noreturn__)) void vex_assert_fail();
+typedef struct {
+  union {
+    struct {
+      UInt imm5;
+    } I5;
+  } ARMri5;
+} ARMRI5;
+typedef enum { ARMin_Alu, ARMin_Shift } ARMInstrTag;
+void iregEnc();
+static UInt skeletal_RI5(ARMRI5 *ri) {
+  UInt imm5 = ri->ARMri5.I5.imm5;
+  __builtin_expect(imm5, 1) ?: vex_assert_fail();
+  iregEnc(ri->ARMri5);
+  return skeletal_RI5_instr;
+}
+ARMInstrTag emit_ARMInstr_i_0;
+void *emit_ARMInstr_disp_cp_chain_me_to_slowEP() {
+  switch (emit_ARMInstr_i_0) {
+  case ARMin_Alu:
+    UInt instr, subopc;
+    UInt rD, rN;
+    goto bad;
+    instr |= subopc | rN;
+  case ARMin_Shift:
+    rD = 0;
+    UInt rM = 0;
+    ARMRI5 argR;
+    instr = skeletal_RI5(&argR);
+    instr |= rD | rM;
+    goto done;
+  }
+bad:
+done:
+  return 0;
+}