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The sequence like this: v_cmpx_le_f32_e32 vcc, 0, v0 s_branch BB0_30 s_cbranch_execnz BB0_30 ; BB#29: exp null off, off, off, off done vm s_endpgm BB0_30: ; %endif110 is likely wrong. The s_branch instruction will unconditionally jump to BB0_30 and the skip block (exp done + endpgm) inserted for performing the kill instruction will never be executed. This results in a GPU hang with Star Ruler 2. The s_branch instruction is added during the "Control Flow Optimizer" pass which seems to re-organize the basic blocks, and we assume that SI_KILL_TERMINATOR is always the last instruction inside a basic block. Thus, after inserting a skip block we just go to the next BB without looking at the subsequent instructions after the kill, and the s_branch op is never removed. Instead, we should remove the unconditional out branches and let skip the two instructions if the exec mask is non-zero. This patch fixes the GPU hang and doesn't introduce any regressions with "make check". Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99019 Patch by Samuel Pitoiset <samuel.pitoiset@gmail.com> llvm-svn: 292985
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