Hi,
On 2019-09-04 07:51:16 -0700, Andres Freund wrote:
> On 2019-09-04 09:56:28 -0400, Jeff Janes wrote:
> > I think it is intuitive, and with empirical evidence, that we do not want
> > to JIT compile at all unless we are going to optimize the compiled code.
>
> There's pretty clear counter-evidence however as well :(
>
> I think it's probably more sensible to use some cheap minimal
> optimization for the "unoptimized" mode - because there's some
> non-linear cost algorithms with full optimizations enabled.
>
> How does your example look with something like:
>
> diff --git i/src/backend/jit/llvm/llvmjit.c w/src/backend/jit/llvm/llvmjit.c
> index 82c4afb7011..85ddae2ea2b 100644
> --- i/src/backend/jit/llvm/llvmjit.c
> +++ w/src/backend/jit/llvm/llvmjit.c
> @@ -428,7 +428,7 @@ llvm_optimize_module(LLVMJitContext *context,
> LLVMModuleRef module)
> if (context->base.flags & PGJIT_OPT3)
> compile_optlevel = 3;
> else
> - compile_optlevel = 0;
> + compile_optlevel = 1;
>
> /*
> * Have to create a new pass manager builder every pass through, as the
>
> which I think - but I'd have to check - doesn't include any of the
> non-linear cost optimizations.
Or better, something slightly more complete, like the attached (which
affects both code-gen time optimizations (which are more like peephole
ones), and both function/global ones that are cheap).
Greetings,
Andres Freund
diff --git i/src/backend/jit/llvm/llvmjit.c w/src/backend/jit/llvm/llvmjit.c
index 82c4afb7011..42cc1b0ab92 100644
--- i/src/backend/jit/llvm/llvmjit.c
+++ w/src/backend/jit/llvm/llvmjit.c
@@ -97,11 +97,11 @@ static const char *llvm_triple = NULL;
static const char *llvm_layout = NULL;
-static LLVMTargetMachineRef llvm_opt0_targetmachine;
+static LLVMTargetMachineRef llvm_opt1_targetmachine;
static LLVMTargetMachineRef llvm_opt3_targetmachine;
static LLVMTargetRef llvm_targetref;
-static LLVMOrcJITStackRef llvm_opt0_orc;
+static LLVMOrcJITStackRef llvm_opt1_orc;
static LLVMOrcJITStackRef llvm_opt3_orc;
@@ -282,12 +282,12 @@ llvm_get_function(LLVMJitContext *context, const char *funcname)
#else
#if LLVM_VERSION_MAJOR < 5
- if ((addr = LLVMOrcGetSymbolAddress(llvm_opt0_orc, funcname)))
+ if ((addr = LLVMOrcGetSymbolAddress(llvm_opt1_orc, funcname)))
return (void *) (uintptr_t) addr;
if ((addr = LLVMOrcGetSymbolAddress(llvm_opt3_orc, funcname)))
return (void *) (uintptr_t) addr;
#else
- if (LLVMOrcGetSymbolAddress(llvm_opt0_orc, &addr, funcname))
+ if (LLVMOrcGetSymbolAddress(llvm_opt1_orc, &addr, funcname))
elog(ERROR, "failed to look up symbol \"%s\"", funcname);
if (addr)
return (void *) (uintptr_t) addr;
@@ -428,7 +428,7 @@ llvm_optimize_module(LLVMJitContext *context, LLVMModuleRef module)
if (context->base.flags & PGJIT_OPT3)
compile_optlevel = 3;
else
- compile_optlevel = 0;
+ compile_optlevel = 1;
/*
* Have to create a new pass manager builder every pass through, as the
@@ -499,7 +499,7 @@ llvm_compile_module(LLVMJitContext *context)
if (context->base.flags & PGJIT_OPT3)
compile_orc = llvm_opt3_orc;
else
- compile_orc = llvm_opt0_orc;
+ compile_orc = llvm_opt1_orc;
/* perform inlining */
if (context->base.flags & PGJIT_INLINE)
@@ -648,9 +648,9 @@ llvm_session_initialize(void)
elog(DEBUG2, "LLVMJIT detected CPU \"%s\", with features \"%s\"",
cpu, features);
- llvm_opt0_targetmachine =
+ llvm_opt1_targetmachine =
LLVMCreateTargetMachine(llvm_targetref, llvm_triple, cpu, features,
- LLVMCodeGenLevelNone,
+ LLVMCodeGenLevelLess,
LLVMRelocDefault,
LLVMCodeModelJITDefault);
llvm_opt3_targetmachine =
@@ -667,7 +667,7 @@ llvm_session_initialize(void)
/* force symbols in main binary to be loaded */
LLVMLoadLibraryPermanently(NULL);
- llvm_opt0_orc = LLVMOrcCreateInstance(llvm_opt0_targetmachine);
+ llvm_opt1_orc = LLVMOrcCreateInstance(llvm_opt1_targetmachine);
llvm_opt3_orc = LLVMOrcCreateInstance(llvm_opt3_targetmachine);
#if defined(HAVE_DECL_LLVMCREATEGDBREGISTRATIONLISTENER) && HAVE_DECL_LLVMCREATEGDBREGISTRATIONLISTENER
@@ -675,7 +675,7 @@ llvm_session_initialize(void)
{
LLVMJITEventListenerRef l = LLVMCreateGDBRegistrationListener();
- LLVMOrcRegisterJITEventListener(llvm_opt0_orc, l);
+ LLVMOrcRegisterJITEventListener(llvm_opt1_orc, l);
LLVMOrcRegisterJITEventListener(llvm_opt3_orc, l);
}
#endif
@@ -684,7 +684,7 @@ llvm_session_initialize(void)
{
LLVMJITEventListenerRef l = LLVMCreatePerfJITEventListener();
- LLVMOrcRegisterJITEventListener(llvm_opt0_orc, l);
+ LLVMOrcRegisterJITEventListener(llvm_opt1_orc, l);
LLVMOrcRegisterJITEventListener(llvm_opt3_orc, l);
}
#endif
@@ -711,14 +711,14 @@ llvm_shutdown(int code, Datum arg)
llvm_opt3_orc = NULL;
}
- if (llvm_opt0_orc)
+ if (llvm_opt1_orc)
{
#if defined(HAVE_DECL_LLVMORCREGISTERPERF) && HAVE_DECL_LLVMORCREGISTERPERF
if (jit_profiling_support)
- LLVMOrcUnregisterPerf(llvm_opt0_orc);
+ LLVMOrcUnregisterPerf(llvm_opt1_orc);
#endif
- LLVMOrcDisposeInstance(llvm_opt0_orc);
- llvm_opt0_orc = NULL;
+ LLVMOrcDisposeInstance(llvm_opt1_orc);
+ llvm_opt1_orc = NULL;
}
}
