Hi!
The following testcase is miscompiled, because the postreload pass changes:
-(insn 14 13 23 2 (parallel [
- (set (reg:DI 1 dx [94])
- (plus:DI (reg:DI 1 dx [95])
- (reg:DI 5 di [92])))
- (clobber (reg:CC 17 flags))
- ]) "pr93402.c":8:30 186 {*adddi_1}
- (expr_list:REG_EQUAL (plus:DI (reg:DI 5 di [92])
- (const_int 111111111111 [0x19debd01c7]))
- (nil)))
-(insn 23 14 25 2 (set (reg:SI 0 ax)
+(insn 23 13 25 2 (set (reg:SI 0 ax)
(const_int 0 [0])) "pr93402.c":10:1 67 {*movsi_internal}
(nil))
(insn 25 23 26 2 (use (reg:SI 0 ax)) "pr93402.c":10:1 -1
(nil))
-(insn 26 25 35 2 (use (reg:DI 1 dx)) "pr93402.c":10:1 -1
+(insn 26 25 35 2 (use (plus:DI (reg:DI 1 dx [95])
+ (reg:DI 5 di [92]))) "pr93402.c":10:1 -1
(nil))
A USE insn is not a normal insn and verify_changes called from
apply_change_group is happy about any changes into it.
The following patch avoids this optimization if we were to change
the USE operand (this routine only changes a reg into (plus reg reg2)).
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk and
later for release branches?
2020-01-23 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/93402
* postreload.c (reload_combine_recognize_pattern): Don't try to adjust
USE insns.
* gcc.c-torture/execute/pr93402.c: New test.
--- gcc/postreload.c.jj 2020-01-12 11:54:36.000000000 +0100
+++ gcc/postreload.c 2020-01-23 17:23:25.359929516 +0100
@@ -1078,6 +1078,10 @@ reload_combine_recognize_pattern (rtx_in
struct reg_use *use = reg_state[regno].reg_use + i;
if (GET_MODE (*use->usep) != mode)
return false;
+ /* Don't try to adjust (use (REGX)). */
+ if (GET_CODE (PATTERN (use->insn)) == USE
+ && &XEXP (PATTERN (use->insn), 0) == use->usep)
+ return false;
}
/* Look for (set (REGX) (CONST_INT))
--- gcc/testsuite/gcc.c-torture/execute/pr93402.c.jj 2020-01-23
17:25:46.496803852 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr93402.c 2020-01-23
17:25:05.221425501 +0100
@@ -0,0 +1,21 @@
+/* PR rtl-optimization/93402 */
+
+struct S { unsigned int a; unsigned long long b; };
+
+__attribute__((noipa)) struct S
+foo (unsigned long long x)
+{
+ struct S ret;
+ ret.a = 0;
+ ret.b = x * 11111111111ULL + 111111111111ULL;
+ return ret;
+}
+
+int
+main ()
+{
+ struct S a = foo (1);
+ if (a.a != 0 || a.b != 122222222222ULL)
+ __builtin_abort ();
+ return 0;
+}
Jakub
