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  • Bug in Radeon GPU's (GCN)

    Hi, guys. I found (in 99% sure) a hardware bug in Radeon GPU's (GCN architecture). Look here: https://community.amd.com/thread/191288.
    I attached simple program that checks results of the S_SUB_I32 instruction including SCC that should hold an overflow of difference two values.
    I ran this program on my Radeon HD 7850. Ofcourse an overflows were incorrect for some cases that program checks.
    My question is: is that bug present in other GCN GPU's? I will be happy, If anybody will attempt to run this simple program on your machine and Radeon GPU's.
    Package contains source code and binaries for Linux (32-bit and 64-bit), so you have to only run this program (no compilation needed).

  • #2
    My bugcheck Fury X results :

    Code:
    C:\Users\Lawrence\radeonbug0>bugcheck64
    Usage: bugcheck GPUDEVICEINDEX
    Using GPU Device #0
    List of devices:
    Device #0, name: Fiji, AddressBits: 64
    Device #1, name: Fiji, AddressBits: 64
    
    Device: Fiji, Driver version: 1800.11
    Loading program binary: bugcheck-Fiji-64-1800.clo
    Calling kernel:
    
    sub_i32 #0: 10213 - 1256: value=8957, scc=0
        Expected value=8957, 64bit: 8957, expected scc=0
    SUCCESS
    
    sub_i32 #1: 13234 - 42221: value=-28987, scc=0
        Expected value=-28987, 64bit: -28987, expected scc=0
    SUCCESS
    
    sub_i32 #2: 6321 - -5343: value=11664, scc=0
        Expected value=11664, 64bit: 11664, expected scc=0
    SUCCESS
    
    sub_i32 #3: 2114067115 - -63823599: value=-2117076582, scc=1
        Expected value=-2117076582, 64bit: 2177890714, expected scc=1
    SUCCESS
    
    sub_i32 #4: -5343 - 6321: value=-11664, scc=0
        Expected value=-11664, 64bit: -11664, expected scc=0
    SUCCESS
    
    sub_i32 #5: -63823599 - 2114067115: value=2117076582, scc=1
        Expected value=2117076582, 64bit: -2177890714, expected scc=1
    SUCCESS
    
    sub_i32 #6: -10213 - -1256: value=-8957, scc=0
        Expected value=-8957, 64bit: -8957, expected scc=0
    SUCCESS
    
    sub_i32 #7: -13234 - -42221: value=28987, scc=0
        Expected value=28987, 64bit: 28987, expected scc=0
    SUCCESS
    
    C:\Users\Lawrence\radeonbug0>bugcheck32
    Usage: bugcheck GPUDEVICEINDEX
    Using GPU Device #0
    List of devices:
    Device #0, name: Fiji, AddressBits: 32
    Device #1, name: Fiji, AddressBits: 32
    
    Device: Fiji, Driver version: 1800.11
    Loading program binary: bugcheck-Fiji-32-1800.clo
    Calling kernel:
    
    sub_i32 #0: 10213 - 1256: value=8957, scc=0
        Expected value=8957, 64bit: 8957, expected scc=0
    SUCCESS
    
    sub_i32 #1: 13234 - 42221: value=-28987, scc=0
        Expected value=-28987, 64bit: -28987, expected scc=0
    SUCCESS
    
    sub_i32 #2: 6321 - -5343: value=11664, scc=0
        Expected value=11664, 64bit: 11664, expected scc=0
    SUCCESS
    
    sub_i32 #3: 2114067115 - -63823599: value=-2117076582, scc=1
        Expected value=-2117076582, 64bit: 2177890714, expected scc=1
    SUCCESS
    
    sub_i32 #4: -5343 - 6321: value=-11664, scc=0
        Expected value=-11664, 64bit: -11664, expected scc=0
    SUCCESS
    
    sub_i32 #5: -63823599 - 2114067115: value=2117076582, scc=1
        Expected value=2117076582, 64bit: -2177890714, expected scc=1
    SUCCESS
    
    sub_i32 #6: -10213 - -1256: value=-8957, scc=0
        Expected value=-8957, 64bit: -8957, expected scc=0
    SUCCESS
    Last edited by DarkFoss; 11-20-2015, 04:24 AM. Reason: both 64 and 32 results

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