C++: Only GVN side-effect-free functions. This improves the performance dramatically.

2026-07-06 12:05:31 +02:00 · 2022-08-25 15:45:50 +01:00
parent fac28ccbe0
commit dc105b404b
7 changed files with 86 additions and 86 deletions
--- a/cpp/ql/lib/semmle/code/cpp/ir/implementation/aliased_ssa/gvn/internal/ValueNumberingImports.qll
+++ b/cpp/ql/lib/semmle/code/cpp/ir/implementation/aliased_ssa/gvn/internal/ValueNumberingImports.qll
@@ -1,3 +1,4 @@
 import semmle.code.cpp.ir.implementation.aliased_ssa.IR
 import semmle.code.cpp.ir.internal.Overlap
 import semmle.code.cpp.ir.internal.IRCppLanguage as Language
+import semmle.code.cpp.models.interfaces.SideEffect as SideEffect
--- a/cpp/ql/lib/semmle/code/cpp/ir/implementation/aliased_ssa/gvn/internal/ValueNumberingInternal.qll
+++ b/cpp/ql/lib/semmle/code/cpp/ir/implementation/aliased_ssa/gvn/internal/ValueNumberingInternal.qll
@@ -44,16 +44,30 @@ newtype TValueNumber =
  TCallValueNumber(TCallPartialValueNumber vn) { callValueNumber(_, _, vn) } or
  TUniqueValueNumber(IRFunction irFunc, Instruction instr) { uniqueValueNumber(instr, irFunc) }

+private class NumberableCallInstruction extends CallInstruction {
+  NumberableCallInstruction() {
+    not this.getResultIRType() instanceof IRVoidType and
+    exists(SideEffect::SideEffectFunction sideEffectFunc |
+      sideEffectFunc = this.getStaticCallTarget()
+    |
+      sideEffectFunc.hasOnlySpecificReadSideEffects() and
+      sideEffectFunc.hasOnlySpecificWriteSideEffects()
+    )
+  }
+}
+
 private newtype TCallPartialValueNumber =
  TNilArgument() or
  TArgument(TCallPartialValueNumber head, TValueNumber arg) {
-    exists(CallInstruction call, int index |
+    exists(NumberableCallInstruction call, int index |
      callArgValueNumber(call, index, arg) and
      callPartialValueNumber(call, index, head)
    )
  }

-private predicate callValueNumber(CallInstruction call, int index, TCallPartialValueNumber vn) {
+private predicate callValueNumber(
+  NumberableCallInstruction call, int index, TCallPartialValueNumber vn
+) {
  index = max(int n | callArgRank(call, n, _) | n) and
  exists(TCallPartialValueNumber head, TValueNumber arg |
    callPartialValueNumber(call, index, pragma[only_bind_out](head)) and
@@ -61,14 +75,15 @@ private predicate callValueNumber(CallInstruction call, int index, TCallPartialV
    vn = TArgument(head, arg)
  )
  or
-  not call.getResultIRType() instanceof IRVoidType and
  not exists(int n | callArgRank(call, n, _)) and
  index = -1 and
  vn = TNilArgument()
 }

-private predicate callPartialValueNumber(CallInstruction call, int index, TCallPartialValueNumber head) {
-  index = 1 and head = TNilArgument() and not call.getResultIRType() instanceof IRVoidType
+private predicate callPartialValueNumber(
+  NumberableCallInstruction call, int index, TCallPartialValueNumber head
+) {
+  index = 1 and head = TNilArgument()
  or
  exists(TCallPartialValueNumber prev, TValueNumber prevVN |
    callPartialValueNumber(call, index - 1, pragma[only_bind_out](prev)) and
@@ -79,8 +94,7 @@ private predicate callPartialValueNumber(CallInstruction call, int index, TCallP

 /**
 */
-private predicate callArgValueNumber(CallInstruction call, int index, TValueNumber arg) {
-  not call.getResultIRType() instanceof IRVoidType and
+private predicate callArgValueNumber(NumberableCallInstruction call, int index, TValueNumber arg) {
  exists(Instruction instr |
    callArgRank(call, index, instr) and
    arg = tvalueNumber(instr)
@@ -91,28 +105,13 @@ private predicate callArgValueNumber(CallInstruction call, int index, TValueNumb
 * Holds if `arg` is the `index`th element in `call`'s extended argument list, including the `this`
 * argument and side-effect reads.
 */
-private predicate callArgRank(CallInstruction call, int index, Instruction arg) {
+private predicate callArgRank(NumberableCallInstruction call, int index, Instruction arg) {
  arg =
    rank[index](int argIndex, boolean isEffect, Instruction instr |
-      exists(CallSideEffectInstruction cse |
-        cse.getPrimaryInstruction() = call and
-        cse.getSideEffectOperand().getAnyDef() = instr and
-        argIndex = -2 and
-        isEffect = true
-      )
-      or
-      exists(CallReadSideEffectInstruction cse |
-        cse.getPrimaryInstruction() = call and
-        cse.getSideEffectOperand().getAnyDef() = instr and
-        argIndex = -2 and
-        isEffect = true
-      )
-      or
-      instr = call.getThisArgument() and
-      argIndex = -1 and
-      isEffect = false
-      or
-      instr = call.getPositionalArgument(argIndex) and
+      // There is no need to include the call's read and write side effects on
+      // all-aliased-memory as `NumberableCallInstruction`s do not read or write
+      // to all-aliased-memory.
+      instr = call.getArgument(argIndex) and
      isEffect = false
      or
      exists(ReadSideEffectInstruction read |
@@ -177,7 +176,7 @@ private predicate numberableInstruction(Instruction instr) {
  or
  instr instanceof LoadTotalOverlapInstruction
  or
-  instr instanceof CallInstruction
+  instr instanceof NumberableCallInstruction
 }

 private predicate filteredNumberableInstruction(Instruction instr) {
--- a/cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/gvn/internal/ValueNumberingImports.qll
+++ b/cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/gvn/internal/ValueNumberingImports.qll
@@ -1,3 +1,4 @@
 import semmle.code.cpp.ir.implementation.aliased_ssa.IR
 import semmle.code.cpp.ir.internal.Overlap
 import semmle.code.cpp.ir.internal.IRCppLanguage as Language
+import semmle.code.cpp.models.interfaces.SideEffect as SideEffect
--- a/cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/gvn/internal/ValueNumberingInternal.qll
+++ b/cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/gvn/internal/ValueNumberingInternal.qll
@@ -44,16 +44,30 @@ newtype TValueNumber =
  TCallValueNumber(TCallPartialValueNumber vn) { callValueNumber(_, _, vn) } or
  TUniqueValueNumber(IRFunction irFunc, Instruction instr) { uniqueValueNumber(instr, irFunc) }

+private class NumberableCallInstruction extends CallInstruction {
+  NumberableCallInstruction() {
+    not this.getResultIRType() instanceof IRVoidType and
+    exists(SideEffect::SideEffectFunction sideEffectFunc |
+      sideEffectFunc = this.getStaticCallTarget()
+    |
+      sideEffectFunc.hasOnlySpecificReadSideEffects() and
+      sideEffectFunc.hasOnlySpecificWriteSideEffects()
+    )
+  }
+}
+
 private newtype TCallPartialValueNumber =
  TNilArgument() or
  TArgument(TCallPartialValueNumber head, TValueNumber arg) {
-    exists(CallInstruction call, int index |
+    exists(NumberableCallInstruction call, int index |
      callArgValueNumber(call, index, arg) and
      callPartialValueNumber(call, index, head)
    )
  }

-private predicate callValueNumber(CallInstruction call, int index, TCallPartialValueNumber vn) {
+private predicate callValueNumber(
+  NumberableCallInstruction call, int index, TCallPartialValueNumber vn
+) {
  index = max(int n | callArgRank(call, n, _) | n) and
  exists(TCallPartialValueNumber head, TValueNumber arg |
    callPartialValueNumber(call, index, pragma[only_bind_out](head)) and
@@ -61,14 +75,15 @@ private predicate callValueNumber(CallInstruction call, int index, TCallPartialV
    vn = TArgument(head, arg)
  )
  or
-  not call.getResultIRType() instanceof IRVoidType and
  not exists(int n | callArgRank(call, n, _)) and
  index = -1 and
  vn = TNilArgument()
 }

-private predicate callPartialValueNumber(CallInstruction call, int index, TCallPartialValueNumber head) {
-  index = 1 and head = TNilArgument() and not call.getResultIRType() instanceof IRVoidType
+private predicate callPartialValueNumber(
+  NumberableCallInstruction call, int index, TCallPartialValueNumber head
+) {
+  index = 1 and head = TNilArgument()
  or
  exists(TCallPartialValueNumber prev, TValueNumber prevVN |
    callPartialValueNumber(call, index - 1, pragma[only_bind_out](prev)) and
@@ -79,8 +94,7 @@ private predicate callPartialValueNumber(CallInstruction call, int index, TCallP

 /**
 */
-private predicate callArgValueNumber(CallInstruction call, int index, TValueNumber arg) {
-  not call.getResultIRType() instanceof IRVoidType and
+private predicate callArgValueNumber(NumberableCallInstruction call, int index, TValueNumber arg) {
  exists(Instruction instr |
    callArgRank(call, index, instr) and
    arg = tvalueNumber(instr)
@@ -91,28 +105,13 @@ private predicate callArgValueNumber(CallInstruction call, int index, TValueNumb
 * Holds if `arg` is the `index`th element in `call`'s extended argument list, including the `this`
 * argument and side-effect reads.
 */
-private predicate callArgRank(CallInstruction call, int index, Instruction arg) {
+private predicate callArgRank(NumberableCallInstruction call, int index, Instruction arg) {
  arg =
    rank[index](int argIndex, boolean isEffect, Instruction instr |
-      exists(CallSideEffectInstruction cse |
-        cse.getPrimaryInstruction() = call and
-        cse.getSideEffectOperand().getAnyDef() = instr and
-        argIndex = -2 and
-        isEffect = true
-      )
-      or
-      exists(CallReadSideEffectInstruction cse |
-        cse.getPrimaryInstruction() = call and
-        cse.getSideEffectOperand().getAnyDef() = instr and
-        argIndex = -2 and
-        isEffect = true
-      )
-      or
-      instr = call.getThisArgument() and
-      argIndex = -1 and
-      isEffect = false
-      or
-      instr = call.getPositionalArgument(argIndex) and
+      // There is no need to include the call's read and write side effects on
+      // all-aliased-memory as `NumberableCallInstruction`s do not read or write
+      // to all-aliased-memory.
+      instr = call.getArgument(argIndex) and
      isEffect = false
      or
      exists(ReadSideEffectInstruction read |
@@ -177,7 +176,7 @@ private predicate numberableInstruction(Instruction instr) {
  or
  instr instanceof LoadTotalOverlapInstruction
  or
-  instr instanceof CallInstruction
+  instr instanceof NumberableCallInstruction
 }

 private predicate filteredNumberableInstruction(Instruction instr) {
--- a/cpp/ql/lib/semmle/code/cpp/ir/implementation/unaliased_ssa/gvn/internal/ValueNumberingImports.qll
+++ b/cpp/ql/lib/semmle/code/cpp/ir/implementation/unaliased_ssa/gvn/internal/ValueNumberingImports.qll
@@ -1,3 +1,4 @@
 import semmle.code.cpp.ir.implementation.aliased_ssa.IR
 import semmle.code.cpp.ir.internal.Overlap
 import semmle.code.cpp.ir.internal.IRCppLanguage as Language
+import semmle.code.cpp.models.interfaces.SideEffect as SideEffect
--- a/cpp/ql/lib/semmle/code/cpp/ir/implementation/unaliased_ssa/gvn/internal/ValueNumberingInternal.qll
+++ b/cpp/ql/lib/semmle/code/cpp/ir/implementation/unaliased_ssa/gvn/internal/ValueNumberingInternal.qll
@@ -44,16 +44,30 @@ newtype TValueNumber =
  TCallValueNumber(TCallPartialValueNumber vn) { callValueNumber(_, _, vn) } or
  TUniqueValueNumber(IRFunction irFunc, Instruction instr) { uniqueValueNumber(instr, irFunc) }

+private class NumberableCallInstruction extends CallInstruction {
+  NumberableCallInstruction() {
+    not this.getResultIRType() instanceof IRVoidType and
+    exists(SideEffect::SideEffectFunction sideEffectFunc |
+      sideEffectFunc = this.getStaticCallTarget()
+    |
+      sideEffectFunc.hasOnlySpecificReadSideEffects() and
+      sideEffectFunc.hasOnlySpecificWriteSideEffects()
+    )
+  }
+}
+
 private newtype TCallPartialValueNumber =
  TNilArgument() or
  TArgument(TCallPartialValueNumber head, TValueNumber arg) {
-    exists(CallInstruction call, int index |
+    exists(NumberableCallInstruction call, int index |
      callArgValueNumber(call, index, arg) and
      callPartialValueNumber(call, index, head)
    )
  }

-private predicate callValueNumber(CallInstruction call, int index, TCallPartialValueNumber vn) {
+private predicate callValueNumber(
+  NumberableCallInstruction call, int index, TCallPartialValueNumber vn
+) {
  index = max(int n | callArgRank(call, n, _) | n) and
  exists(TCallPartialValueNumber head, TValueNumber arg |
    callPartialValueNumber(call, index, pragma[only_bind_out](head)) and
@@ -61,14 +75,15 @@ private predicate callValueNumber(CallInstruction call, int index, TCallPartialV
    vn = TArgument(head, arg)
  )
  or
-  not call.getResultIRType() instanceof IRVoidType and
  not exists(int n | callArgRank(call, n, _)) and
  index = -1 and
  vn = TNilArgument()
 }

-private predicate callPartialValueNumber(CallInstruction call, int index, TCallPartialValueNumber head) {
-  index = 1 and head = TNilArgument() and not call.getResultIRType() instanceof IRVoidType
+private predicate callPartialValueNumber(
+  NumberableCallInstruction call, int index, TCallPartialValueNumber head
+) {
+  index = 1 and head = TNilArgument()
  or
  exists(TCallPartialValueNumber prev, TValueNumber prevVN |
    callPartialValueNumber(call, index - 1, pragma[only_bind_out](prev)) and
@@ -79,8 +94,7 @@ private predicate callPartialValueNumber(CallInstruction call, int index, TCallP

 /**
 */
-private predicate callArgValueNumber(CallInstruction call, int index, TValueNumber arg) {
-  not call.getResultIRType() instanceof IRVoidType and
+private predicate callArgValueNumber(NumberableCallInstruction call, int index, TValueNumber arg) {
  exists(Instruction instr |
    callArgRank(call, index, instr) and
    arg = tvalueNumber(instr)
@@ -91,28 +105,13 @@ private predicate callArgValueNumber(CallInstruction call, int index, TValueNumb
 * Holds if `arg` is the `index`th element in `call`'s extended argument list, including the `this`
 * argument and side-effect reads.
 */
-private predicate callArgRank(CallInstruction call, int index, Instruction arg) {
+private predicate callArgRank(NumberableCallInstruction call, int index, Instruction arg) {
  arg =
    rank[index](int argIndex, boolean isEffect, Instruction instr |
-      exists(CallSideEffectInstruction cse |
-        cse.getPrimaryInstruction() = call and
-        cse.getSideEffectOperand().getAnyDef() = instr and
-        argIndex = -2 and
-        isEffect = true
-      )
-      or
-      exists(CallReadSideEffectInstruction cse |
-        cse.getPrimaryInstruction() = call and
-        cse.getSideEffectOperand().getAnyDef() = instr and
-        argIndex = -2 and
-        isEffect = true
-      )
-      or
-      instr = call.getThisArgument() and
-      argIndex = -1 and
-      isEffect = false
-      or
-      instr = call.getPositionalArgument(argIndex) and
+      // There is no need to include the call's read and write side effects on
+      // all-aliased-memory as `NumberableCallInstruction`s do not read or write
+      // to all-aliased-memory.
+      instr = call.getArgument(argIndex) and
      isEffect = false
      or
      exists(ReadSideEffectInstruction read |
@@ -177,7 +176,7 @@ private predicate numberableInstruction(Instruction instr) {
  or
  instr instanceof LoadTotalOverlapInstruction
  or
-  instr instanceof CallInstruction
+  instr instanceof NumberableCallInstruction
 }

 private predicate filteredNumberableInstruction(Instruction instr) {
--- a/cpp/ql/test/library-tests/valuenumbering/GlobalValueNumbering/ir_gvn.expected
+++ b/cpp/ql/test/library-tests/valuenumbering/GlobalValueNumbering/ir_gvn.expected
@@ -1325,7 +1325,7 @@ test.cpp:
 #  176|     r176_3(int)            = Constant[2]                  : 
 #  176|         valnum = r176_3, r178_3
 #  176|     r176_4(int)            = Call[add]                    : func:r176_1, 0:r176_2, 1:r176_3
-#  176|         valnum = r176_4, r178_4
+#  176|         valnum = unique
 #  177|     r177_1(glval<unknown>) = FunctionAddress[add]         : 
 #  177|         valnum = unique
 #  177|     r177_2(int)            = Constant[3]                  : 
@@ -1341,7 +1341,7 @@ test.cpp:
 #  178|     r178_3(int)            = Constant[2]                  : 
 #  178|         valnum = r176_3, r178_3
 #  178|     r178_4(int)            = Call[add]                    : func:r178_1, 0:r178_2, 1:r178_3
-#  178|         valnum = r176_4, r178_4
+#  178|         valnum = unique
 #  179|     v179_1(void)           = NoOp                         : 
 #  165|     v165_13(void)          = ReturnIndirection[dst]       : &:r165_7, m171_11
 #  165|     v165_14(void)          = ReturnIndirection[src]       : &:r165_11, m165_12