[clang] Enable FPContract with optnone

Previously treatment of the attribute `optnone` was modified in llvm#85605 ([clang] Set correct FPOptions if attribute 'optnone' presents). As a side effect FPContract was disabled for optnone. It created unneeded divergence with the behavior of -O0, which enables this optimization. In the discussion llvm#85605 (comment) it was pointed out that FP contraction should be enabled even if all optimizations are turned off, otherwise results of calculations would be different. This change enables FPContract at optnone.
spavloff · May 4, 2024 · 32c0ec8 · 32c0ec8
1 parent 1aeb64c
commit 32c0ec8
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Showing 4 changed files with 15 additions and 16 deletions.
diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
@@ -970,7 +970,6 @@ class FPOptionsOverride {
 
   void setDisallowOptimizations() {
     setFPPreciseEnabled(true);
-    setDisallowFPContract();
   }
 
   storage_type getAsOpaqueInt() const {

diff --git a/clang/test/AST/ast-dump-fpfeatures.cpp b/clang/test/AST/ast-dump-fpfeatures.cpp
@@ -198,7 +198,7 @@ float func_19(float x, float y) {
 // CHECK-LABEL: FunctionDecl {{.*}} func_19 'float (float, float)'
 // CHECK:         CompoundStmt {{.*}} MathErrno=1
 // CHECK:           ReturnStmt
-// CHECK:             BinaryOperator {{.*}} 'float' '+' ConstRoundingMode=downward MathErrno=1
+// CHECK:             BinaryOperator {{.*}} 'float' '+' FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 
 __attribute__((optnone))
 float func_20(float x, float y) try {
@@ -210,7 +210,7 @@ float func_20(float x, float y) try {
 // CHECK-LABEL: FunctionDecl {{.*}} func_20 'float (float, float)'
 // CHECK:         CompoundStmt {{.*}} ConstRoundingMode=downward MathErrno=1
 // CHECK:           ReturnStmt
-// CHECK:             BinaryOperator {{.*}} 'float' '+' ConstRoundingMode=downward MathErrno=1
+// CHECK:             BinaryOperator {{.*}} 'float' '+' FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 
 struct C21 {
   C21(float x, float y);
@@ -221,15 +221,15 @@ struct C21 {
 };
 
 // CHECK-LABEL: CXXMethodDecl {{.*}} a_method 'float (float, float)'
-// CHECK:         CompoundStmt {{.*}} ConstRoundingMode=downward MathErrno=1
+// CHECK:         CompoundStmt {{.*}} FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 // CHECK:           ReturnStmt
-// CHECK:             BinaryOperator {{.*}} 'float' '*' ConstRoundingMode=downward MathErrno=1
+// CHECK:             BinaryOperator {{.*}} 'float' '*' FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 
 __attribute__((optnone)) C21::C21(float x, float y) : member(x + y) {}
 
 // CHECK-LABEL: CXXConstructorDecl {{.*}} C21 'void (float, float)'
 // CHECK:         CXXCtorInitializer {{.*}} 'member' 'float'
-// CHECK:           BinaryOperator {{.*}} 'float' '+' ConstRoundingMode=downward MathErrno=1
+// CHECK:           BinaryOperator {{.*}} 'float' '+' FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 
 template <typename T>
 __attribute__((optnone)) T func_22(T x, T y) {
@@ -238,13 +238,13 @@ __attribute__((optnone)) T func_22(T x, T y) {
 
 // CHECK-LABEL: FunctionTemplateDecl {{.*}} func_22
 // CHECK:         FunctionDecl {{.*}} func_22 'T (T, T)'
-// CHECK:           CompoundStmt {{.*}} ConstRoundingMode=downward MathErrno=1
+// CHECK:           CompoundStmt {{.*}} FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 // CHECK:             ReturnStmt
-// CHECK:               BinaryOperator {{.*}} '+' ConstRoundingMode=downward MathErrno=1
+// CHECK:               BinaryOperator {{.*}} '+' FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 // CHECK:         FunctionDecl {{.*}} func_22 'float (float, float)'
-// CHECK:           CompoundStmt {{.*}} ConstRoundingMode=downward MathErrno=1
+// CHECK:           CompoundStmt {{.*}} FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 // CHECK:             ReturnStmt
-// CHECK:               BinaryOperator {{.*}} 'float' '+' ConstRoundingMode=downward MathErrno=1
+// CHECK:               BinaryOperator {{.*}} 'float' '+' FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 
 float func_23(float x, float y) {
   return func_22(x, y);

diff --git a/clang/test/AST/ast-dump-fpfeatures.m b/clang/test/AST/ast-dump-fpfeatures.m
@@ -24,6 +24,6 @@ - (float) sum: (float)x with: (float)y __attribute((optnone)) {
 
 // CHECK-LABEL: ObjCImplementationDecl {{.*}} Adder
 // CHECK:         ObjCMethodDecl {{.*}} - sum:with: 'float'
-// CHECK:           CompoundStmt {{.*}} MathErrno=1
+// CHECK:           CompoundStmt {{.*}} FPContractMode=1 MathErrno=1
 // CHECK-NEXT:        ReturnStmt
-// CHECK-NEXT:          BinaryOperator {{.*}} 'float' '+' MathErrno=1
+// CHECK-NEXT:          BinaryOperator {{.*}} 'float' '+' FPContractMode=1 MathErrno=1
diff --git a/clang/test/AST/ast-dump-late-parsing.cpp b/clang/test/AST/ast-dump-late-parsing.cpp
@@ -11,13 +11,13 @@ __attribute__((optnone)) T func_22(T x, T y) {
 
 // CHECK-LABEL: FunctionTemplateDecl {{.*}} func_22
 // CHECK:         FunctionDecl {{.*}} func_22 'T (T, T)'
-// CHECK:           CompoundStmt {{.*}} ConstRoundingMode=downward MathErrno=1
+// CHECK:           CompoundStmt {{.*}} FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 // CHECK:             ReturnStmt
-// CHECK:               BinaryOperator {{.*}} '+' ConstRoundingMode=downward MathErrno=1
+// CHECK:               BinaryOperator {{.*}} '+' FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 // CHECK:         FunctionDecl {{.*}} func_22 'float (float, float)'
-// CHECK:           CompoundStmt {{.*}} ConstRoundingMode=downward MathErrno=1
+// CHECK:           CompoundStmt {{.*}} FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 // CHECK:             ReturnStmt
-// CHECK:               BinaryOperator {{.*}} 'float' '+' ConstRoundingMode=downward MathErrno=1
+// CHECK:               BinaryOperator {{.*}} 'float' '+' FPContractMode=1 ConstRoundingMode=downward MathErrno=1
 
 float func_23(float x, float y) {
   return func_22(x, y);