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Fix PR2343. An *interesting* coalescer bug.

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BB1:                                                                                                                                                  
  vr1025 = copy vr1024                                                                                                                                
  ..                                                                                                                                                  
BB2:                                                                                                                                                  
  vr1024 = op                                                                                                                                         
         = op vr1025                                                                                                                                     
  <loop eventually branch back to BB1>

Even though vr1025 is copied from vr1024, it's not safe to coalesced them since live range of vr1025 intersects the def of vr1024. This happens when vr1025 is assigned the value of the previous iteration of vr1024 in the loop.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51394 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2008-05-21 22:34:12 +00:00
parent 40db5d4539
commit f4ea510371
2 changed files with 124 additions and 1 deletions
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28
lib/CodeGen/SimpleRegisterCoalescing.cpp
View File

@ -1322,7 +1322,20 @@ bool SimpleRegisterCoalescing::SimpleJoin(LiveInterval &LHS, LiveInterval &RHS){
// Copy from the RHS?
if (!RangeIsDefinedByCopyFromReg(LHS, LHSIt, RHS.reg))
return false; // Nope, bail out.
if (LHSIt->contains(RHSIt->valno->def))
// Here is an interesting situation:
// BB1:
// vr1025 = copy vr1024
// ..
// BB2:
// vr1024 = op
// = vr1025
// Even though vr1025 is copied from vr1024, it's not safe to
// coalesced them since live range of vr1025 intersects the
// def of vr1024. This happens because vr1025 is assigned the
// value of the previous iteration of vr1024.
return false;
EliminatedLHSVals.push_back(LHSIt->valno);
}
@ -1348,6 +1361,19 @@ bool SimpleRegisterCoalescing::SimpleJoin(LiveInterval &LHS, LiveInterval &RHS){
// Otherwise, if this is a copy from the RHS, mark it as being merged
// in.
if (RangeIsDefinedByCopyFromReg(LHS, LHSIt, RHS.reg)) {
if (LHSIt->contains(RHSIt->valno->def))
// Here is an interesting situation:
// BB1:
// vr1025 = copy vr1024
// ..
// BB2:
// vr1024 = op
// = vr1025
// Even though vr1025 is copied from vr1024, it's not safe to
// coalesced them since live range of vr1025 intersects the
// def of vr1024. This happens because vr1025 is assigned the
// value of the previous iteration of vr1024.
return false;
EliminatedLHSVals.push_back(LHSIt->valno);
// We know this entire LHS live range is okay, so skip it now.

97
test/CodeGen/X86/2008-05-21-CoalescerBug.ll Normal file
View File

@ -0,0 +1,97 @@
; RUN: llvm-as < %s | llc -march=x86 -fast | grep mov | count 4
; PR2343
%llvm.dbg.anchor.type = type { i32, i32 }
%struct.CUMULATIVE_ARGS = type { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }
%struct.VEC_basic_block_base = type { i32, i32, [1 x %struct.basic_block_def*] }
%struct.VEC_basic_block_gc = type { %struct.VEC_basic_block_base }
%struct.VEC_edge_base = type { i32, i32, [1 x %struct.edge_def*] }
%struct.VEC_edge_gc = type { %struct.VEC_edge_base }
%struct.VEC_rtx_base = type { i32, i32, [1 x %struct.rtx_def*] }
%struct.VEC_rtx_gc = type { %struct.VEC_rtx_base }
%struct.VEC_temp_slot_p_base = type { i32, i32, [1 x %struct.temp_slot*] }
%struct.VEC_temp_slot_p_gc = type { %struct.VEC_temp_slot_p_base }
%struct.VEC_tree_base = type { i32, i32, [1 x %struct.tree_node*] }
%struct.VEC_tree_gc = type { %struct.VEC_tree_base }
%struct.__sbuf = type { i8*, i32 }
%struct._obstack_chunk = type { i8*, %struct._obstack_chunk*, [4 x i8] }
%struct.basic_block_def = type { %struct.tree_node*, %struct.VEC_edge_gc*, %struct.VEC_edge_gc*, i8*, %struct.loop*, [2 x %struct.et_node*], %struct.basic_block_def*, %struct.basic_block_def*, %struct.basic_block_il_dependent, %struct.tree_node*, %struct.edge_prediction*, i64, i32, i32, i32, i32 }
%struct.basic_block_il_dependent = type { %struct.rtl_bb_info* }
%struct.bitmap_element_def = type { %struct.bitmap_element_def*, %struct.bitmap_element_def*, i32, [4 x i32] }
%struct.bitmap_head_def = type { %struct.bitmap_element_def*, %struct.bitmap_element_def*, i32, %struct.bitmap_obstack* }
%struct.bitmap_obstack = type { %struct.bitmap_element_def*, %struct.bitmap_head_def*, %struct.obstack }
%struct.block_symbol = type { [3 x %struct.cfg_stats_d], %struct.object_block*, i64 }
%struct.cfg_stats_d = type { i32 }
%struct.control_flow_graph = type { %struct.basic_block_def*, %struct.basic_block_def*, %struct.VEC_basic_block_gc*, i32, i32, i32, %struct.VEC_basic_block_gc*, i32 }
%struct.def_optype_d = type { %struct.def_optype_d*, %struct.tree_node** }
%struct.edge_def = type { %struct.basic_block_def*, %struct.basic_block_def*, %struct.edge_def_insns, i8*, %struct.__sbuf*, i32, i32, i64, i32 }
%struct.edge_def_insns = type { %struct.rtx_def* }
%struct.edge_prediction = type { %struct.edge_prediction*, %struct.edge_def*, i32, i32 }
%struct.eh_status = type opaque
%struct.emit_status = type { i32, i32, %struct.rtx_def*, %struct.rtx_def*, %struct.sequence_stack*, i32, %struct.__sbuf, i32, i8*, %struct.rtx_def** }
%struct.et_node = type opaque
%struct.expr_status = type { i32, i32, i32, %struct.rtx_def*, %struct.rtx_def*, %struct.rtx_def* }
%struct.function = type { %struct.eh_status*, %struct.expr_status*, %struct.emit_status*, %struct.varasm_status*, %struct.control_flow_graph*, %struct.tree_node*, %struct.function*, i32, i32, i32, i32, %struct.rtx_def*, %struct.CUMULATIVE_ARGS, %struct.rtx_def*, %struct.rtx_def*, %struct.initial_value_struct*, %struct.rtx_def*, %struct.rtx_def*, %struct.rtx_def*, %struct.rtx_def*, %struct.rtx_def*, %struct.rtx_def*, i8, i32, i64, %struct.tree_node*, %struct.tree_node*, %struct.rtx_def*, %struct.VEC_temp_slot_p_gc*, %struct.temp_slot*, %struct.var_refs_queue*, i32, i32, i32, i32, %struct.machine_function*, i32, i32, %struct.language_function*, %struct.htab*, %struct.rtx_def*, i32, i32, i32, %struct.__sbuf, %struct.VEC_tree_gc*, %struct.tree_node*, i8*, i8*, i8*, i8*, i8*, %struct.tree_node*, i8, i8, i8, i8, i8, i8 }
%struct.htab = type { i32 (i8*)*, i32 (i8*, i8*)*, void (i8*)*, i8**, i32, i32, i32, i32, i32, i8* (i32, i32)*, void (i8*)*, i8*, i8* (i8*, i32, i32)*, void (i8*, i8*)*, i32 }
%struct.initial_value_struct = type opaque
%struct.lang_decl = type opaque
%struct.language_function = type opaque
%struct.loop = type { i32, %struct.basic_block_def*, %struct.basic_block_def*, %llvm.dbg.anchor.type, i32, i32, i32, i32, %struct.loop**, i32, %struct.loop*, %struct.loop*, %struct.loop*, %struct.loop*, i8*, %struct.tree_node*, %struct.tree_node*, %struct.nb_iter_bound*, %struct.edge_def*, i32 }
%struct.machine_function = type opaque
%struct.maydef_optype_d = type { %struct.maydef_optype_d*, %struct.tree_node*, %struct.tree_node*, %struct.ssa_use_operand_d }
%struct.nb_iter_bound = type { %struct.tree_node*, %struct.tree_node*, %struct.nb_iter_bound* }
%struct.object_block = type { %struct.section*, i32, i64, %struct.VEC_rtx_gc*, %struct.VEC_rtx_gc* }
%struct.obstack = type { i32, %struct._obstack_chunk*, i8*, i8*, i8*, i32, i32, %struct._obstack_chunk* (i8*, i32)*, void (i8*, %struct._obstack_chunk*)*, i8*, i8 }
%struct.rtl_bb_info = type { %struct.rtx_def*, %struct.rtx_def*, %struct.bitmap_head_def*, %struct.bitmap_head_def*, %struct.rtx_def*, %struct.rtx_def*, i32 }
%struct.rtx_def = type { i16, i8, i8, %struct.u }
%struct.section = type { %struct.unnamed_section }
%struct.sequence_stack = type { %struct.rtx_def*, %struct.rtx_def*, %struct.sequence_stack* }
%struct.ssa_use_operand_d = type { %struct.ssa_use_operand_d*, %struct.ssa_use_operand_d*, %struct.tree_node*, %struct.tree_node** }
%struct.stmt_ann_d = type { %struct.tree_ann_common_d, i8, %struct.basic_block_def*, %struct.stmt_operands_d, %struct.bitmap_head_def*, i32, i8* }
%struct.stmt_operands_d = type { %struct.def_optype_d*, %struct.use_optype_d*, %struct.maydef_optype_d*, %struct.vuse_optype_d*, %struct.maydef_optype_d* }
%struct.temp_slot = type opaque
%struct.tree_ann_common_d = type { i32, i8*, %struct.tree_node* }
%struct.tree_ann_d = type { %struct.stmt_ann_d }
%struct.tree_common = type { %struct.tree_node*, %struct.tree_node*, %struct.tree_ann_d*, i8, i8, i8, i8, i8 }
%struct.tree_decl_common = type { %struct.tree_decl_minimal, %struct.tree_node*, i8, i8, i8, i8, i8, i32, %struct.tree_decl_u1, %struct.tree_node*, %struct.tree_node*, %struct.tree_node*, %struct.tree_node*, i64, %struct.lang_decl* }
%struct.tree_decl_minimal = type { %struct.tree_common, %struct.__sbuf, i32, %struct.tree_node*, %struct.tree_node* }
%struct.tree_decl_non_common = type { %struct.tree_decl_with_vis, %struct.tree_node*, %struct.tree_node*, %struct.tree_node*, %struct.tree_node* }
%struct.tree_decl_u1 = type { i64 }
%struct.tree_decl_with_rtl = type { %struct.tree_decl_common, %struct.rtx_def*, i32 }
%struct.tree_decl_with_vis = type { %struct.tree_decl_with_rtl, %struct.tree_node*, %struct.tree_node*, i8, i8, i8 }
%struct.tree_function_decl = type { %struct.tree_decl_non_common, i8, i8, i64, %struct.function* }
%struct.tree_node = type { %struct.tree_function_decl }
%struct.u = type { %struct.block_symbol }
%struct.unnamed_section = type { %struct.cfg_stats_d, void (i8*)*, i8*, %struct.section* }
%struct.use_optype_d = type { %struct.use_optype_d*, %struct.ssa_use_operand_d }
%struct.var_refs_queue = type { %struct.rtx_def*, i32, i32, %struct.var_refs_queue* }
%struct.varasm_status = type opaque
%struct.vuse_optype_d = type { %struct.vuse_optype_d*, %struct.tree_node*, %struct.ssa_use_operand_d }
@llvm.used = appending global [1 x i8*] [ i8* bitcast (%struct.edge_def* (%struct.edge_def*, %struct.basic_block_def*)* @tree_redirect_edge_and_branch to i8*) ], section "llvm.metadata" ; <[1 x i8*]*> [#uses=0]
define %struct.edge_def* @tree_redirect_edge_and_branch(%struct.edge_def* %e1, %struct.basic_block_def* %dest2) nounwind {
entry:
br label %bb497
bb483: ; preds = %bb497
%tmp496 = load %struct.tree_node** null, align 4 ; <%struct.tree_node*> [#uses=1]
br label %bb497
bb497: ; preds = %bb483, %entry
%cases.0 = phi %struct.tree_node* [ %tmp496, %bb483 ], [ null, %entry ] ; <%struct.tree_node*> [#uses=1]
%last.0 = phi %struct.tree_node* [ %cases.0, %bb483 ], [ undef, %entry ] ; <%struct.tree_node*> [#uses=1]
br i1 false, label %bb483, label %bb502
bb502: ; preds = %bb497
br i1 false, label %bb507, label %bb841
bb507: ; preds = %bb502
%tmp517 = getelementptr %struct.tree_node* %last.0, i32 0, i32 0 ; <%struct.tree_function_decl*> [#uses=1]
%tmp517518 = bitcast %struct.tree_function_decl* %tmp517 to %struct.tree_common* ; <%struct.tree_common*> [#uses=1]
%tmp519 = getelementptr %struct.tree_common* %tmp517518, i32 0, i32 0 ; <%struct.tree_node**> [#uses=1]
store %struct.tree_node* null, %struct.tree_node** %tmp519, align 4
br label %bb841
bb841: ; preds = %bb507, %bb502
unreachable
}