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Fix false positives when utilizing OSL's "debug_uninit" feature #1947

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lgritz merged 4 commits into from
Feb 25, 2025
Merged

Fix false positives when utilizing OSL's "debug_uninit" feature #1947

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c3eba39
Fix false positives when utilizing OSL's "debug_uninit" feature. It …
AlexMWells Feb 24, 2025
a9bccb5
clang formatting changes
AlexMWells Feb 24, 2025
778c97f
more clang formatting
AlexMWells Feb 24, 2025
0eb25de
Merge branch 'main' into PR/DebugUninitFalsePositives
AlexMWells Feb 24, 2025
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116 changes: 86 additions & 30 deletions src/liboslexec/batched_llvm_instance.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -138,6 +138,9 @@ static ustring op_aref("aref");
static ustring op_compref("compref");
static ustring op_mxcompref("mxcompref");
static ustring op_useparam("useparam");
static ustring op_pointcloud_get("pointcloud_get");
static ustring op_spline("spline");
static ustring op_splineinverse("splineinverse");
static ustring unknown_shader_group_name("<Unknown Shader Group Name>");


Expand Down Expand Up @@ -1620,7 +1623,8 @@ BatchedBackendLLVM::llvm_generate_debug_uninit(const Opcode& op)
}

llvm::Value* ncheck = ll.constant(int(t.numelements() * t.aggregate));
llvm::Value* offset = ll.constant(0);
llvm::Value* varying_nchecks = nullptr;
llvm::Value* offset = ll.constant(0);
BatchedBackendLLVM::TempScope temp_scope(*this);
llvm::Value* loc_varying_offsets = nullptr;

Expand Down Expand Up @@ -1701,6 +1705,31 @@ BatchedBackendLLVM::llvm_generate_debug_uninit(const Opcode& op)
ll.op_store(comp, loc_varying_offsets);
}
ncheck = ll.constant(1);
} else if (op.opname() == op_pointcloud_get && i == 2) {
// int pointcloud_get (string ptcname, int indices[], int count, string attr, type data[])
// will only read indices[0..count-1], so limit the check to count
OSL_ASSERT(3 < op.nargs());
Symbol& count_sym = *opargsym(op, 3);
if (count_sym.is_uniform()) {
ncheck = llvm_load_value(count_sym);
} else {
// Don't think we can have a uniform indices array that
// has a varying index count
if (!sym.is_uniform()) {
varying_nchecks = ll.void_ptr(llvm_get_pointer(count_sym));
}
}
} else if (((op.opname() == op_spline)
|| (op.opname() == op_splineinverse))
&& i == 4) {
// If an explicit knot count was provided to spline|splineinverse we should
// limit our check of knot values to that count
bool has_knot_count = (op.nargs() == 5);
if (has_knot_count) {
Symbol& knot_count_sym = *opargsym(op, 3);
OSL_ASSERT(knot_count_sym.is_uniform());
ncheck = llvm_load_value(knot_count_sym);
}
}

if (loc_varying_offsets != nullptr) {
Expand All @@ -1724,15 +1753,15 @@ BatchedBackendLLVM::llvm_generate_debug_uninit(const Opcode& op)
if (sym.is_uniform()) {
ll.call_function(build_name(
FuncSpec("uninit_check_values_offset")
.arg_uniform(TypeDesc::PTR)
.arg_varying(TypeInt)
.arg_uniform(TypeDesc::PTR) // vals
.arg_varying(TypeInt) // firstcheck
.mask()),
args);
} else {
ll.call_function(build_name(
FuncSpec("uninit_check_values_offset")
.arg_varying(TypeDesc::PTR)
.arg_varying(TypeInt)
.arg_varying(TypeDesc::PTR) // vals
.arg_varying(TypeInt) // firstcheck
.mask()),
args);
}
Expand All @@ -1756,33 +1785,60 @@ BatchedBackendLLVM::llvm_generate_debug_uninit(const Opcode& op)
ncheck };
ll.call_function(build_name(
FuncSpec("uninit_check_values_offset")
.arg_uniform(TypeDesc::PTR)
.arg_uniform(TypeInt)),
.arg_uniform(TypeDesc::PTR) // vals
.arg_uniform(TypeInt)), // firstcheck
args);
} else {
llvm::Value* args[]
= { ll.mask_as_int(ll.current_mask()),
ll.constant(t),
llvm_void_ptr(sym),
sg_void_ptr(),
ll.constant(op.sourcefile()),
ll.constant(op.sourceline()),
ll.constant(group().name()),
ll.constant(layer()),
ll.constant(inst()->layername()),
ll.constant(inst()->shadername().c_str()),
ll.constant(int(&op - &inst()->ops()[0])),
ll.constant(op.opname()),
ll.constant(i),
ll.constant(sym.unmangled()),
offset,
ncheck };
ll.call_function(build_name(
FuncSpec("uninit_check_values_offset")
.arg_varying(TypeDesc::PTR)
.arg_uniform(TypeInt)
.mask()),
args);
if (varying_nchecks != nullptr) {
llvm::Value* args[]
= { ll.mask_as_int(ll.current_mask()),
ll.constant(t),
llvm_void_ptr(sym),
sg_void_ptr(),
ll.constant(op.sourcefile()),
ll.constant(op.sourceline()),
ll.constant(group().name()),
ll.constant(layer()),
ll.constant(inst()->layername()),
ll.constant(inst()->shadername().c_str()),
ll.constant(int(&op - &inst()->ops()[0])),
ll.constant(op.opname()),
ll.constant(i),
ll.constant(sym.unmangled()),
offset,
varying_nchecks };
ll.call_function(
build_name(FuncSpec("uninit_check_values_offset")
.arg_varying(TypeDesc::PTR) // vals
.arg_uniform(TypeInt) // firstcheck
.arg_varying(TypeInt) // nchecks
.mask()),
args);
} else {
llvm::Value* args[]
= { ll.mask_as_int(ll.current_mask()),
ll.constant(t),
llvm_void_ptr(sym),
sg_void_ptr(),
ll.constant(op.sourcefile()),
ll.constant(op.sourceline()),
ll.constant(group().name()),
ll.constant(layer()),
ll.constant(inst()->layername()),
ll.constant(inst()->shadername().c_str()),
ll.constant(int(&op - &inst()->ops()[0])),
ll.constant(op.opname()),
ll.constant(i),
ll.constant(sym.unmangled()),
offset,
ncheck };
ll.call_function(
build_name(FuncSpec("uninit_check_values_offset")
.arg_varying(TypeDesc::PTR) // vals
.arg_uniform(TypeInt) // firstcheck
.mask()),
args);
}
}
}
}
Expand Down
2 changes: 2 additions & 0 deletions src/liboslexec/builtindecl_wide_xmacro.h
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Original file line number Diff line number Diff line change
Expand Up @@ -373,6 +373,8 @@ DECL(__OSL_MASKED_OP(range_check), "xXiisXsisiss")
DECL(__OSL_OP2(uninit_check_values_offset, X, i), "xLXXsisissisisii")
DECL(__OSL_MASKED_OP2(uninit_check_values_offset, X, Wi), "xiLXXsisissisisXi")
DECL(__OSL_MASKED_OP2(uninit_check_values_offset, WX, i), "xiLXXsisissisisii")
DECL(__OSL_MASKED_OP3(uninit_check_values_offset, WX, i, Wi),
"xiLXXsisissisisiX")
DECL(__OSL_MASKED_OP2(uninit_check_values_offset, WX, Wi), "xiLXXsisissisisXi")

DECL(__OSL_OP1(get_attribute, s), "iXissiiXXi")
Expand Down
23 changes: 21 additions & 2 deletions src/liboslexec/llvm_instance.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -143,6 +143,9 @@ static ustring op_aref("aref");
static ustring op_compref("compref");
static ustring op_mxcompref("mxcompref");
static ustring op_useparam("useparam");
static ustring op_pointcloud_get("pointcloud_get");
static ustring op_spline("spline");
static ustring op_splineinverse("splineinverse");
static ustring unknown_shader_group_name("<Unknown Shader Group Name>");


Expand Down Expand Up @@ -1135,8 +1138,10 @@ BackendLLVM::llvm_generate_debug_uninit(const Opcode& op)
// don't generate uninit test code for it.
continue;
}
if (op.opname() == Strings::op_dowhile && i == 0) {
// The first argument of 'dowhile' is the condition temp, but
if (((op.opname() == Strings::op_dowhile)
|| (op.opname() == Strings::op_while))
&& i == 0) {
// The first argument of 'dowhile' or "while" is the condition temp, but
// most likely its initializer has not run yet. Unless there is
// no "condition" code block, in that case we should still test
// it for uninit.
Expand Down Expand Up @@ -1185,6 +1190,20 @@ BackendLLVM::llvm_generate_debug_uninit(const Opcode& op)
comp = ll.op_add(comp, col_ind);
offset = comp;
ncheck = ll.constant(1);
} else if (op.opname() == op_pointcloud_get && i == 2) {
// int pointcloud_get (string ptcname, int indices[], int count, string attr, type data[])
// will only read indices[0..count-1], so limit the check to count
OSL_ASSERT(3 < op.nargs());
ncheck = llvm_load_value(*opargsym(op, 3));
} else if (((op.opname() == op_spline)
|| (op.opname() == op_splineinverse))
&& i == 4) {
// If an explicit knot count was provided to spline|splineinverse we should
// limit our check of knot values to that count
bool has_knot_count = (op.nargs() == 5);
if (has_knot_count) {
ncheck = llvm_load_value(*opargsym(op, 3));
}
}

llvm::Value* args[] = { ll.constant(t),
Expand Down
90 changes: 82 additions & 8 deletions src/liboslexec/wide/wide_shadingsys.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -169,10 +169,10 @@ __OSL_OP2(uninit_check_values_offset, X,
ustring layername = USTR(layername_);
ctx->errorfmt(
"Detected possible use of uninitialized value in {} {} at {}:{} (group {}, layer {} {}, shader {}, op {} '{}', arg {})",
typedesc, symbolname, sourcefile, sourceline,
typedesc, USTR(symbolname), USTR(sourcefile), sourceline,
groupname.empty() ? "<unnamed group>" : groupname.c_str(), layer,
layername.empty() ? "<unnamed layer>" : layername.c_str(),
shadername, opnum, opname, argnum);
USTR(shadername), opnum, USTR(opname), argnum);
}
}

Expand Down Expand Up @@ -233,10 +233,82 @@ __OSL_MASKED_OP2(uninit_check_values_offset, WX,
ustring layername = USTR(layername_);
ctx->errorfmt(
"Detected possible use of uninitialized value in {} {} at {}:{} (group {}, layer {} {}, shader {}, op {} '{}', arg {}) for lanes({:x}) of batch",
typedesc, symbolname, sourcefile, sourceline,
typedesc, USTR(symbolname), USTR(sourcefile), sourceline,
groupname.empty() ? "<unnamed group>" : groupname.c_str(), layer,
layername.empty() ? "<unnamed layer>" : layername.c_str(),
shadername, opnum, opname, argnum, lanes_uninit.value());
USTR(shadername), opnum, USTR(opname), argnum,
lanes_uninit.value());
}
}



// Many parameters, but the 3 parameters used in the function name
// correspond to: "vals", "firstcheck", and "nchecks"
OSL_BATCHOP void
__OSL_MASKED_OP3(uninit_check_values_offset, WX, i,
Wi)(int mask_value, long long typedesc_, void* vals_,
void* bsg_, ustring_pod sourcefile, int sourceline,
ustring_pod groupname_, int layer, ustring_pod layername_,
ustring_pod shadername, int opnum, ustring_pod opname,
int argnum, ustring_pod symbolname, int firstcheck,
int* nchecks_)
{
TypeDesc typedesc = TYPEDESC(typedesc_);
auto* bsg = reinterpret_cast<BatchedShaderGlobals*>(bsg_);
ShadingContext* ctx = bsg->uniform.context;
const Mask mask(mask_value);

Mask lanes_uninit(false);

if (typedesc.basetype == TypeDesc::FLOAT) {
float* vals = (float*)vals_;
mask.foreach ([=, &lanes_uninit](ActiveLane lane) -> void {
int nchecks = nchecks_[lane];
for (int c = firstcheck, e = firstcheck + nchecks; c < e; ++c) {
if (!std::isfinite(vals[c * __OSL_WIDTH + lane])) {
lanes_uninit.set_on(lane);
vals[c * __OSL_WIDTH + lane] = 0;
}
}
});
}
if (typedesc.basetype == TypeDesc::INT) {
int* vals = (int*)vals_;
mask.foreach ([=, &lanes_uninit](ActiveLane lane) -> void {
int nchecks = nchecks_[lane];
for (int c = firstcheck, e = firstcheck + nchecks; c < e; ++c) {
if (vals[c * __OSL_WIDTH + lane]
== std::numeric_limits<int>::min()) {
lanes_uninit.set_on(lane);
vals[c * __OSL_WIDTH + lane] = 0;
}
}
});
}
if (typedesc.basetype == TypeDesc::STRING) {
ustring* vals = (ustring*)vals_;
mask.foreach ([=, &lanes_uninit](ActiveLane lane) -> void {
int nchecks = nchecks_[lane];
for (int c = firstcheck, e = firstcheck + nchecks; c < e; ++c) {
if (vals[c * __OSL_WIDTH + lane]
== Strings::uninitialized_string) {
lanes_uninit.set_on(lane);
vals[c * __OSL_WIDTH + lane] = ustring();
}
}
});
}
if (lanes_uninit.any_on()) {
ustring groupname = USTR(groupname_);
ustring layername = USTR(layername_);
ctx->errorfmt(
"Detected possible use of uninitialized value in {} {} at {}:{} (group {}, layer {} {}, shader {}, op {} '{}', arg {}) for lanes({:x}) of batch",
typedesc, USTR(symbolname), USTR(sourcefile), sourceline,
groupname.empty() ? "<unnamed group>" : groupname.c_str(), layer,
layername.empty() ? "<unnamed layer>" : layername.c_str(),
USTR(shadername), opnum, USTR(opname), argnum,
lanes_uninit.value());
}
}

Expand Down Expand Up @@ -299,10 +371,11 @@ __OSL_MASKED_OP2(uninit_check_values_offset, X,
ustring layername = USTR(layername_);
ctx->errorfmt(
"Detected possible use of uninitialized value in {} {} at {}:{} (group {}, layer {} {}, shader {}, op {} '{}', arg {}) for lanes({:x}) of batch",
typedesc, symbolname, sourcefile, sourceline,
typedesc, USTR(symbolname), USTR(sourcefile), sourceline,
groupname.empty() ? "<unnamed group>" : groupname.c_str(), layer,
layername.empty() ? "<unnamed layer>" : layername.c_str(),
shadername, opnum, opname, argnum, lanes_uninit.value());
USTR(shadername), opnum, USTR(opname), argnum,
lanes_uninit.value());
}
}

Expand Down Expand Up @@ -367,10 +440,11 @@ __OSL_MASKED_OP2(uninit_check_values_offset, WX,
ustring layername = USTR(layername_);
ctx->errorfmt(
"Detected possible use of uninitialized value in {} {} at {}:{} (group {}, layer {} {}, shader {}, op {} '{}', arg {}) for lanes({:x}) of batch",
typedesc, symbolname, sourcefile, sourceline,
typedesc, USTR(symbolname), USTR(sourcefile), sourceline,
groupname.empty() ? "<unnamed group>" : groupname.c_str(), layer,
layername.empty() ? "<unnamed layer>" : layername.c_str(),
shadername, opnum, opname, argnum, lanes_uninit.value());
USTR(shadername), opnum, USTR(opname), argnum,
lanes_uninit.value());
}
}

Expand Down
2 changes: 2 additions & 0 deletions testsuite/debug-uninit/ref/out-opt2.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -8,3 +8,5 @@ ERROR: [RendererServices::texture] ImageInput::create() called with no filename
ERROR: Detected possible use of uninitialized value in float[3] A at test.osl:22 (group unnamed_group_1, layer 0 test_0, shader test, op 7 'aref', arg 1)
ERROR: Detected possible use of uninitialized value in color C at test.osl:28 (group unnamed_group_1, layer 0 test_0, shader test, op 12 'compref', arg 1)
ERROR: Detected possible use of uninitialized value in matrix M at test.osl:34 (group unnamed_group_1, layer 0 test_0, shader test, op 17 'mxcompref', arg 1)
ERROR: Detected possible use of uninitialized value in float[20] knots3 at test.osl:54 (group unnamed_group_1, layer 0 test_0, shader test, op 44 'spline', arg 4)
ERROR: Detected possible use of uninitialized value in float[20] knots4 at test.osl:55 (group unnamed_group_1, layer 0 test_0, shader test, op 46 'splineinverse', arg 4)
2 changes: 2 additions & 0 deletions testsuite/debug-uninit/ref/out.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -8,3 +8,5 @@ ERROR: [RendererServices::texture] ImageInput::create() called with no filename
ERROR: Detected possible use of uninitialized value in float[3] A at test.osl:22 (group unnamed_group_1, layer 0 test_0, shader test, op 12 'aref', arg 1)
ERROR: Detected possible use of uninitialized value in color C at test.osl:28 (group unnamed_group_1, layer 0 test_0, shader test, op 17 'compref', arg 1)
ERROR: Detected possible use of uninitialized value in matrix M at test.osl:34 (group unnamed_group_1, layer 0 test_0, shader test, op 22 'mxcompref', arg 1)
ERROR: Detected possible use of uninitialized value in float[20] knots3 at test.osl:54 (group unnamed_group_1, layer 0 test_0, shader test, op 49 'spline', arg 4)
ERROR: Detected possible use of uninitialized value in float[20] knots4 at test.osl:55 (group unnamed_group_1, layer 0 test_0, shader test, op 51 'splineinverse', arg 4)
24 changes: 24 additions & 0 deletions testsuite/debug-uninit/test.osl
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Expand Up @@ -33,5 +33,29 @@ test (output color Cout = 0)
x += M[1][2]; // NOT an error
x += M[0][0]; // An error
}
float knots[20];
float knots2[20];
float knots3[20];
float knots4[20];
int index=0;
// Ensure no false positive for temporary condition variable
while (index < 10) {
knots[index] = x*index;
knots2[index] = (1.0-x)*index;
knots3[index] = 2*x*index;
knots4[index] = 2*(1.0-x)*index;
++index;
}
// Ensure no false positive for accessing initialized portion of a partially initialized array
x += spline ("linear", x, 10, knots);
x += splineinverse ("linear", x, 10, knots2);

// Accessing uninitialized portion of a partially initialized array
x += spline ("linear", x, 15, knots3);
x += splineinverse ("linear", x, 15, knots4);

// pointcloud_get could also have false postive and read partially initialized array
// leaving pointcloud_get out, as not all builds are configured for pointcloud support

Cout[0] += x; // force x results to not be optimized away
}
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