https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113356
--- Comment #2 from Alex Coplan <acoplan at gcc dot gnu.org> --- So we have this IR: insn i8 in bb2 [ebb2] at point 18: +---------------------------- | 8: [r104:DI++]=r101:DI | REG_DEAD r101:DI | REG_INC r104:DI +---------------------------- has pre/post-modify operations uses: use of set r101:i7 (DI pseudo) use of set r104:i17 (DI pseudo) appears in a read/write context defines: set r104:i8 (DI pseudo) set by a pre/post-modify appears in a read/write context used by insn i13 in bb2 [ebb2] at point 24 set mem:i8 insn i11 in bb2 [ebb2] at point 20: +------------------------------------------------ | 11: r106:DI=high(const(`_ZTV6Class1'+0x10)) +------------------------------------------------ defines: set r106:i11 (DI pseudo) used by insn i12 in bb2 [ebb2] at point 22 insn i12 in bb2 [ebb2] at point 22: +------------------------------------------------------- | 12: r105:DI=r106:DI+low(const(`_ZTV6Class1'+0x10)) | REG_DEAD r106:DI | REG_EQUAL const(`_ZTV6Class1'+0x10) +------------------------------------------------------- uses: use of set r106:i11 (DI pseudo) defines: set r105:i12 (DI pseudo) used by insn i13 in bb2 [ebb2] at point 24 insn i13 in bb2 [ebb2] at point 24: +---------------------------------------- | 13: [r104:DI]=r105:DI | REG_DEAD r105:DI | REG_DEAD r104:DI | REG_EH_REGION 0xffffffffffffffff +---------------------------------------- uses: use of set r104:i8 (DI pseudo) appears inside an address use of set r105:i12 (DI pseudo) defines: set mem:i13 used by phi node mem:a7 in ebb1 at point 30 and we're trying to form (8,13). i8 has i13 as a hazard due to the writeback dataflow and i13 has i12 as a hazard (due to the initial fix for non-call exceptions introducing a hazard on the previous nondebug insn). I wonder if it would be enough to get i