clang, clang++, gcc, g++: edit page (#11629)

pages/common/clang++.md

@@ -23,3 +23,7 @@
 - Compile source code into LLVM Intermediate Representation (IR):
 
 `clang++ -S -emit-llvm {{path/to/source.cpp}} -o {{path/to/output.ll}}`
+
+- Optimize the compiled program for performance:
+
+`clang++ {{path/to/source.cpp}} -O{{1|2|3|fast}} -o {{path/to/output_executable}}`

pages/common/clang.md

@@ -22,3 +22,7 @@
 - Compile source code without linking:
 
 `clang -c {{input_source.c}}`
+
+- Optimize the compiled program for performance:
+
+`clang {{path/to/source.c}} -O{{1|2|3|fast}}`

pages/common/g++.md

@@ -24,6 +24,10 @@
 
 `g++ -c {{path/to/source_1.cpp path/to/source_2.cpp ...}} && g++ -o {{path/to/output_executable}} {{path/to/source_1.o path/to/source_2.o ...}}`
 
+- Optimize the compiled program for performance:
+
+`g++ {{path/to/source.cpp}} -O{{1|2|3|fast}} -o {{path/to/output_executable}}`
+
 - Display version:
 
 `g++ --version`

pages/common/gcc.md

@@ -22,3 +22,7 @@
 - Compile source code into an object file without linking:
 
 `gcc -c {{path/to/source.c}}`
+
+- Optimize the compiled program for performance:
+
+`gcc {{path/to/source.c}} -O{{1|2|3|fast}}`