[libc] Use ${libc_opt_high_flag} instead of -O3 (#123233)

This is preferable since `${libc_opt_high_flag}` will be set correctly
for the compiler used.

libc/cmake/modules/LLVMLibCTestRules.cmake

@@ -223,6 +223,8 @@ function(create_libc_unittest fq_target_name)
 
   _get_common_test_compile_options(compile_options "${LIBC_UNITTEST_C_TEST}"
                                    "${LIBC_UNITTEST_FLAGS}")
+  # TODO: Ideally we would have a separate function for link options.
+  set(link_options ${compile_options})
   list(APPEND compile_options ${LIBC_UNITTEST_COMPILE_OPTIONS})
 
   if(SHOW_INTERMEDIATE_OBJECTS)
@@ -277,7 +279,7 @@ function(create_libc_unittest fq_target_name)
   target_include_directories(${fq_build_target_name} SYSTEM PRIVATE ${LIBC_INCLUDE_DIR})
   target_include_directories(${fq_build_target_name} PRIVATE ${LIBC_SOURCE_DIR})
   target_compile_options(${fq_build_target_name} PRIVATE ${compile_options})
-  target_link_options(${fq_build_target_name} PRIVATE ${compile_options})
+  target_link_options(${fq_build_target_name} PRIVATE ${link_options})
 
   if(NOT LIBC_UNITTEST_CXX_STANDARD)
     set(LIBC_UNITTEST_CXX_STANDARD ${CMAKE_CXX_STANDARD})

libc/src/math/generic/CMakeLists.txt

@@ -534,7 +534,7 @@ add_entrypoint_object(
     libc.src.__support.macros.optimization
     libc.src.__support.macros.properties.types
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
 )
 
 add_entrypoint_object(

libc/test/src/__support/CMakeLists.txt

@@ -234,7 +234,7 @@ add_libc_test(
     libc.src.stdlib.srand
     libc.src.string.memset
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
   UNIT_TEST_ONLY
     # Aligned Allocation is not supported in hermetic builds.
 )

libc/test/src/math/CMakeLists.txt

@@ -1597,7 +1597,7 @@ add_fp_unittest(
     libc.src.math.sqrtf
     libc.src.__support.FPUtil.generic.sqrt
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
 )
 
 add_fp_unittest(
@@ -1613,7 +1613,7 @@ add_fp_unittest(
     libc.src.math.sqrt
     libc.src.__support.FPUtil.generic.sqrt
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
 )
 
 add_fp_unittest(
@@ -1629,7 +1629,7 @@ add_fp_unittest(
     libc.src.math.sqrtl
     libc.src.__support.FPUtil.generic.sqrt
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
 )
 
 add_fp_unittest(

libc/test/src/math/exhaustive/CMakeLists.txt

@@ -305,7 +305,7 @@ add_fp_unittest(
   SRCS
     hypotf_test.cpp
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
   DEPENDS
     .exhaustive_test
     libc.src.math.hypotf

libc/test/src/math/smoke/CMakeLists.txt

@@ -2993,7 +2993,7 @@ add_fp_unittest(
   DEPENDS
     libc.src.__support.FPUtil.generic.sqrt
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
 )
 
 add_fp_unittest(
@@ -3007,7 +3007,7 @@ add_fp_unittest(
   DEPENDS
     libc.src.__support.FPUtil.generic.sqrt
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
 )
 
 add_fp_unittest(
@@ -3021,7 +3021,7 @@ add_fp_unittest(
   DEPENDS
     libc.src.__support.FPUtil.generic.sqrt
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
 )
 
 add_fp_unittest(
@@ -3038,7 +3038,7 @@ add_fp_unittest(
     libc.src.math.sqrtf128
     libc.src.__support.FPUtil.generic.sqrt
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
 )
 
 add_fp_unittest(

libc/test/src/stdfix/CMakeLists.txt

@@ -14,7 +14,7 @@ foreach(suffix IN ITEMS hr r lr hk k lk)
     SRCS
       abs${suffix}_test.cpp
     COMPILE_OPTIONS
-      -O3
+      ${libc_opt_high_flag}
     DEPENDS
       libc.src.stdfix.abs${suffix}
       libc.src.__support.fixed_point.fx_bits
@@ -31,7 +31,7 @@ foreach(suffix IN ITEMS uhr ur ulr uhk uk)
     SRCS
       sqrt${suffix}_test.cpp
     COMPILE_OPTIONS
-      -O3
+      ${libc_opt_high_flag}
     DEPENDS
       libc.src.stdfix.sqrt${suffix}
       libc.src.__support.CPP.bit
@@ -52,7 +52,7 @@ foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
     SRCS
       round${suffix}_test.cpp
     COMPILE_OPTIONS
-      -O3
+      ${libc_opt_high_flag}
     DEPENDS
       libc.src.stdfix.round${suffix}
       libc.src.__support.fixed_point.fx_bits
@@ -67,7 +67,7 @@ foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
     SRCS
       ${suffix}bits_test.cpp
     COMPILE_OPTIONS
-      -O3
+      ${libc_opt_high_flag}
     DEPENDS
       libc.src.stdfix.${suffix}bits
       libc.src.__support.CPP.bit
@@ -84,7 +84,7 @@ add_libc_test(
   SRCS
     uhksqrtus_test.cpp
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
   DEPENDS
     libc.src.stdfix.uhksqrtus
     libc.src.__support.CPP.bit
@@ -103,7 +103,7 @@ add_libc_test(
   SRCS
     uksqrtui_test.cpp
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
   DEPENDS
     libc.src.stdfix.uksqrtui
     libc.src.__support.CPP.bit
@@ -122,7 +122,7 @@ add_libc_test(
   SRCS
     exphk_test.cpp
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
   DEPENDS
     libc.src.stdfix.exphk
     libc.src.math.exp
@@ -140,7 +140,7 @@ add_libc_test(
   SRCS
     expk_test.cpp
   COMPILE_OPTIONS
-    -O3
+    ${libc_opt_high_flag}
   DEPENDS
     libc.src.stdfix.expk
     libc.src.math.exp

libc/utils/MPFRWrapper/CMakeLists.txt

@@ -34,7 +34,7 @@ if(LIBC_TESTS_CAN_USE_MPFR)
   _get_common_test_compile_options(compile_options "" "")
   # mpfr/gmp headers do not work with -ffreestanding flag.
   list(REMOVE_ITEM compile_options "-ffreestanding")
-  target_compile_options(libcMPFRWrapper PRIVATE -O3 ${compile_options})
+  target_compile_options(libcMPFRWrapper PRIVATE ${libc_opt_high_flag} ${compile_options})
   add_dependencies(
     libcMPFRWrapper
     libcMPCommon