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Remove many LLVM optimization passes which were causes UB due to them assuming C-like behaviour incompatible with Odin

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This commit is contained in:
gingerBill
2021-11-06 17:23:33 +00:00
parent 5df15b5724
commit 3d3785a7f1
6 changed files with 83 additions and 41 deletions
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src/llvm_backend_opt.cpp
+53 -27
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@@ -1,3 +1,36 @@
/**************************************************************************
IMPORTANT NOTE(bill, 2021-11-06): Regarding Optimization Passes
A lot of the passes taken here have been modified with what was
partially done in LLVM 11.
Passes that CANNOT be used by Odin due to C-like optimizations which
are not compatible with Odin:
LLVMAddCorrelatedValuePropagationPass
LLVMAddAggressiveInstCombinerPass
LLVMAddInstructionCombiningPass
LLVMAddIndVarSimplifyPass
LLVMAddLoopUnrollPass
LLVMAddEarlyCSEMemSSAPass
LLVMAddGVNPass
Odin does not allow poison-value based optimizations.
For example, *-flowing integers in C is "undefined behaviour" and thus
many optimizers, including LLVM, take advantage of this for a certain
class of optimizations. Odin on the other hand defines *-flowing
behaviour to obey the rules of 2's complement, meaning wrapping is a
expected. This means any outputted IR containing the following flags
may cause incorrect behaviour:
nsw (no signed wrap)
nuw (no unsigned wrap)
poison (poison value)
**************************************************************************/
void lb_populate_function_pass_manager(lbModule *m, LLVMPassManagerRef fpm, bool ignore_memcpy_pass, i32 optimization_level);
void lb_add_function_simplifcation_passes(LLVMPassManagerRef mpm, i32 optimization_level);
void lb_populate_module_pass_manager(LLVMTargetMachineRef target_machine, LLVMPassManagerRef mpm, i32 optimization_level);
@@ -33,10 +66,10 @@ void lb_basic_populate_function_pass_manager(LLVMPassManagerRef fpm) {
LLVM_ADD_CONSTANT_VALUE_PASS(fpm);
LLVMAddEarlyCSEPass(fpm);
LLVM_ADD_CONSTANT_VALUE_PASS(fpm);
LLVMAddMergedLoadStoreMotionPass(fpm);
LLVMAddPromoteMemoryToRegisterPass(fpm);
LLVMAddCFGSimplificationPass(fpm);
// LLVM_ADD_CONSTANT_VALUE_PASS(fpm);
// LLVMAddMergedLoadStoreMotionPass(fpm);
// LLVMAddPromoteMemoryToRegisterPass(fpm);
// LLVMAddCFGSimplificationPass(fpm);
}
void lb_populate_function_pass_manager(lbModule *m, LLVMPassManagerRef fpm, bool ignore_memcpy_pass, i32 optimization_level) {
@@ -61,6 +94,7 @@ void lb_populate_function_pass_manager(lbModule *m, LLVMPassManagerRef fpm, bool
LLVMPassManagerBuilderSetSizeLevel(pmb, optimization_level);
LLVMPassManagerBuilderPopulateFunctionPassManager(pmb, fpm);
#else
LLVMAddMemCpyOptPass(fpm);
lb_basic_populate_function_pass_manager(fpm);
LLVMAddSCCPPass(fpm);
@@ -116,17 +150,10 @@ void lb_populate_function_pass_manager_specific(lbModule *m, LLVMPassManagerRef
}
void lb_add_function_simplifcation_passes(LLVMPassManagerRef mpm, i32 optimization_level) {
LLVMAddEarlyCSEMemSSAPass(mpm);
LLVMAddGVNPass(mpm);
LLVMAddCFGSimplificationPass(mpm);
LLVMAddJumpThreadingPass(mpm);
// if (optimization_level > 2) {
// LLVMAddAggressiveInstCombinerPass(mpm);
// }
LLVMAddInstructionCombiningPass(mpm);
LLVMAddSimplifyLibCallsPass(mpm);
LLVMAddTailCallEliminationPass(mpm);
@@ -138,23 +165,16 @@ void lb_add_function_simplifcation_passes(LLVMPassManagerRef mpm, i32 optimizati
LLVMAddLoopUnswitchPass(mpm);
LLVMAddCFGSimplificationPass(mpm);
LLVMAddInstructionCombiningPass(mpm);
LLVMAddIndVarSimplifyPass(mpm);
LLVMAddLoopIdiomPass(mpm);
LLVMAddLoopDeletionPass(mpm);
LLVMAddLoopUnrollPass(mpm);
LLVMAddMergedLoadStoreMotionPass(mpm);
LLVMAddGVNPass(mpm);
LLVMAddMemCpyOptPass(mpm);
LLVMAddSCCPPass(mpm);
LLVMAddBitTrackingDCEPass(mpm);
LLVMAddInstructionCombiningPass(mpm);
LLVMAddJumpThreadingPass(mpm);
LLVM_ADD_CONSTANT_VALUE_PASS(mpm);
LLVMAddDeadStoreEliminationPass(mpm);
@@ -163,7 +183,6 @@ void lb_add_function_simplifcation_passes(LLVMPassManagerRef mpm, i32 optimizati
LLVMAddLoopRerollPass(mpm);
LLVMAddAggressiveDCEPass(mpm);
LLVMAddCFGSimplificationPass(mpm);
LLVMAddInstructionCombiningPass(mpm);
}
@@ -191,6 +210,7 @@ void lb_populate_module_pass_manager(LLVMTargetMachineRef target_machine, LLVMPa
// LLVMPassManagerBuilderPopulateLTOPassManager(pmb, mpm, false, true);
// return;
}
LLVMAddIPSCCPPass(mpm);
LLVMAddCalledValuePropagationPass(mpm);
@@ -198,8 +218,6 @@ void lb_populate_module_pass_manager(LLVMTargetMachineRef target_machine, LLVMPa
LLVMAddGlobalOptimizerPass(mpm);
LLVMAddDeadArgEliminationPass(mpm);
// LLVMAddConstantMergePass(mpm); // ???
LLVMAddInstructionCombiningPass(mpm);
LLVMAddCFGSimplificationPass(mpm);
LLVMAddPruneEHPass(mpm);
@@ -208,25 +226,24 @@ void lb_populate_module_pass_manager(LLVMTargetMachineRef target_machine, LLVMPa
}
LLVMAddFunctionInliningPass(mpm);
lb_add_function_simplifcation_passes(mpm, optimization_level);
LLVMAddGlobalDCEPass(mpm);
LLVMAddGlobalOptimizerPass(mpm);
// LLVMAddLowerConstantIntrinsicsPass(mpm);
LLVMAddLoopRotatePass(mpm);
LLVMAddLoopVectorizePass(mpm);
LLVMAddInstructionCombiningPass(mpm);
if (optimization_level >= 2) {
LLVMAddEarlyCSEPass(mpm);
LLVM_ADD_CONSTANT_VALUE_PASS(mpm);
LLVMAddLICMPass(mpm);
LLVMAddLoopUnswitchPass(mpm);
LLVMAddCFGSimplificationPass(mpm);
LLVMAddInstructionCombiningPass(mpm);
}
LLVMAddCFGSimplificationPass(mpm);
@@ -246,6 +263,15 @@ void lb_populate_module_pass_manager(LLVMTargetMachineRef target_machine, LLVMPa
LLVMAddCFGSimplificationPass(mpm);
}
/**************************************************************************
IMPORTANT NOTE(bill, 2021-11-06): Custom Passes
The procedures below are custom written passes to aid in the
optimization of Odin programs
**************************************************************************/
void lb_run_remove_dead_instruction_pass(lbProcedure *p) {
isize removal_count = 0;
isize pass_count = 0;