James Hogan dba4828444 tcg/mips: Fix clobbering of qemu_ld inputs ... The MIPS TCG backend implements qemu_ld with 64-bit targets using the v0 register (base) as a temporary to load the upper half of the QEMU TLB comparator (see line 5 below), however this happens before the input address is used (line 8 to mask off the low bits for the TLB comparison, and line 12 to add the host-guest offset). If the input address (addrl) also happens to have been placed in v0 (as in the second column below), it gets clobbered before it is used. addrl in t2 addrl in v0 1 srl a0,t2,0x7 srl a0,v0,0x7 2 andi a0,a0,0x1fe0 andi a0,a0,0x1fe0 3 addu a0,a0,s0 addu a0,a0,s0 4 lw at,9136(a0) lw at,9136(a0) set TCG_TMP0 (at) 5 lw v0,9140(a0) lw v0,9140(a0) set base (v0) 6 li t9,-4093 li t9,-4093 7 lw a0,9160(a0) lw a0,9160(a0) set addend (a0) 8 and t9,t9,t2 and t9,t9,v0 use addrl 9 bne at,t9,0x836d8c8 bne at,t9,0x836d838 use TCG_TMP0 10 nop nop 11 bne v0,t8,0x836d8c8 bne v0,a1,0x836d838 use base 12 addu v0,a0,t2 addu v0,a0,v0 use addrl, addend 13 lw t0,0(v0) lw t0,0(v0) Fix by using TCG_TMP0 (at) as the temporary instead of v0 (base), pushing the load on line 5 forward into the delay slot of the low comparison (line 10). The early load of the addend on line 7 also needs pushing even further for 64-bit targets, or it will clobber a0 before we're done with it. The output for 32-bit targets is unaffected. srl a0,v0,0x7 andi a0,a0,0x1fe0 addu a0,a0,s0 lw at,9136(a0) -lw v0,9140(a0) load high comparator li t9,-4093 -lw a0,9160(a0) load addend and t9,t9,v0 bne at,t9,0x836d838 - nop + lw at,9140(a0) load high comparator +lw a0,9160(a0) load addend -bne v0,a1,0x836d838 +bne at,a1,0x836d838 addu v0,a0,v0 lw t0,0(v0) Backports commit 33fca8589cf2aa7bf91564e6a8f26b3ba0910541 from qemu		2018-02-17 15:23:24 -05:00
..
tcg-target.c	tcg/mips: Fix clobbering of qemu_ld inputs	2018-02-17 15:23:24 -05:00
tcg-target.h	tcg: add TCG_TARGET_TLB_DISPLACEMENT_BITS	2018-02-13 08:28:29 -05:00