[flang] Warn when F128 is unsupported (#102147) #106957

tblah · 2024-09-02T09:42:11Z

This generates warning: REAL(KIND=16) is not an enabled type for this target if that type is used in a build not correctly configured to support this type. Uses of selected_real_kind(30) return -1.

Relanding #102147 because the test errors turned out to be specific to a downstream configuration.

This generates `warning: REAL(KIND=16) is not an enabled type for this target` if that type is used in a build not correctly configured to support this type. Uses of `selected_real_kind(30)` return -1.

llvmbot · 2024-09-02T09:42:44Z

@llvm/pr-subscribers-flang-fir-hlfir

@llvm/pr-subscribers-flang-semantics

Author: Tom Eccles (tblah)

Changes

This generates warning: REAL(KIND=16) is not an enabled type for this target if that type is used in a build not correctly configured to support this type. Uses of selected_real_kind(30) return -1.

Relanding #102147 because the test errors turned out to be specific to a downstream configuration.

Full diff: https://github.com/llvm/llvm-project/pull/106957.diff

14 Files Affected:

(modified) flang/include/flang/Tools/TargetSetup.h (+18-1)
(modified) flang/module/ieee_arithmetic.f90 (+49)
(modified) flang/test/CMakeLists.txt (+10)
(modified) flang/test/Evaluate/fold-out_of_range.f90 (+1)
(modified) flang/test/Evaluate/folding07.f90 (+1)
(modified) flang/test/Lower/Intrinsics/ieee_class_queries.f90 (+1)
(modified) flang/test/Lower/Intrinsics/ieee_unordered.f90 (+1)
(modified) flang/test/Lower/common-block.f90 (+1-1)
(modified) flang/test/Semantics/kinds03.f90 (+1)
(modified) flang/test/Semantics/modfile26.f90 (+1)
(modified) flang/test/Semantics/realkinds-aarch64-01.f90 (+1)
(modified) flang/test/lit.cfg.py (+2-1)
(modified) flang/test/lit.site.cfg.py.in (+1)
(modified) flang/tools/f18/CMakeLists.txt (+24-1)

diff --git a/flang/include/flang/Tools/TargetSetup.h b/flang/include/flang/Tools/TargetSetup.h
index 238d66c9241dd0..60609de8809cf0 100644
--- a/flang/include/flang/Tools/TargetSetup.h
+++ b/flang/include/flang/Tools/TargetSetup.h
@@ -11,6 +11,7 @@
 
 #include "flang/Evaluate/target.h"
 #include "llvm/Target/TargetMachine.h"
+#include <cfloat>
 
 namespace Fortran::tools {
 
@@ -21,9 +22,25 @@ namespace Fortran::tools {
 
   const llvm::Triple &targetTriple{targetMachine.getTargetTriple()};
   // FIXME: Handle real(3) ?
-  if (targetTriple.getArch() != llvm::Triple::ArchType::x86_64)
+  if (targetTriple.getArch() != llvm::Triple::ArchType::x86_64) {
     targetCharacteristics.DisableType(
         Fortran::common::TypeCategory::Real, /*kind=*/10);
+  }
+
+  // Figure out if we can support F128: see
+  // flang/runtime/Float128Math/math-entries.h
+#ifdef FLANG_RUNTIME_F128_MATH_LIB
+  // we can use libquadmath wrappers
+  constexpr bool f128Support = true;
+#elif LDBL_MANT_DIG == 113
+  // we can use libm wrappers
+  constexpr bool f128Support = true;
+#else
+  constexpr bool f128Support = false;
+#endif
+
+  if constexpr (!f128Support)
+    targetCharacteristics.DisableType(Fortran::common::TypeCategory::Real, 16);
 
   targetCharacteristics.set_compilerOptionsString(compilerOptions)
       .set_compilerVersionString(compilerVersion);
diff --git a/flang/module/ieee_arithmetic.f90 b/flang/module/ieee_arithmetic.f90
index 7c7721d78c1ed3..32e640b9e24574 100644
--- a/flang/module/ieee_arithmetic.f90
+++ b/flang/module/ieee_arithmetic.f90
@@ -161,6 +161,8 @@ end function ieee_round_ne
   G(1) G(2) G(4) G(8) G(16)
 #define SPECIFICS_L(G) \
   G(1) G(2) G(4) G(8)
+
+#if FLANG_SUPPORT_R16
 #if __x86_64__
 #define SPECIFICS_R(G) \
   G(2) G(3) G(4) G(8) G(10) G(16)
@@ -168,12 +170,24 @@ end function ieee_round_ne
 #define SPECIFICS_R(G) \
   G(2) G(3) G(4) G(8) G(16)
 #endif
+#else
+#if __x86_64__
+#define SPECIFICS_R(G) \
+  G(2) G(3) G(4) G(8) G(10)
+#else
+#define SPECIFICS_R(G) \
+  G(2) G(3) G(4) G(8)
+#endif
+#endif
+
 #define SPECIFICS_II(G) \
   G(1,1) G(1,2) G(1,4) G(1,8) G(1,16) \
   G(2,1) G(2,2) G(2,4) G(2,8) G(2,16) \
   G(4,1) G(4,2) G(4,4) G(4,8) G(4,16) \
   G(8,1) G(8,2) G(8,4) G(8,8) G(8,16) \
   G(16,1) G(16,2) G(16,4) G(16,8) G(16,16)
+
+#if FLANG_SUPPORT_R16
 #if __x86_64__
 #define SPECIFICS_RI(G) \
   G(2,1) G(2,2) G(2,4) G(2,8) G(2,16) \
@@ -190,7 +204,24 @@ end function ieee_round_ne
   G(8,1) G(8,2) G(8,4) G(8,8) G(8,16) \
   G(16,1) G(16,2) G(16,4) G(16,8) G(16,16)
 #endif
+#else
+#if __x86_64__
+#define SPECIFICS_RI(G) \
+  G(2,1) G(2,2) G(2,4) G(2,8) \
+  G(3,1) G(3,2) G(3,4) G(3,8) \
+  G(4,1) G(4,2) G(4,4) G(4,8) \
+  G(8,1) G(8,2) G(8,4) G(8,8) \
+  G(10,1) G(10,2) G(10,4) G(10,8)
+#else
+#define SPECIFICS_RI(G) \
+  G(2,1) G(2,2) G(2,4) G(2,8) \
+  G(3,1) G(3,2) G(3,4) G(3,8) \
+  G(4,1) G(4,2) G(4,4) G(4,8) \
+  G(8,1) G(8,2) G(8,4) G(8,8)
+#endif
+#endif
 
+#if FLANG_SUPPORT_R16
 #if __x86_64__
 #define SPECIFICS_RR(G) \
   G(2,2) G(2,3) G(2,4) G(2,8) G(2,10) G(2,16) \
@@ -207,6 +238,22 @@ end function ieee_round_ne
   G(8,2) G(8,3) G(8,4) G(8,8) G(8,16) \
   G(16,2) G(16,3) G(16,4) G(16,8) G(16,16)
 #endif
+#else
+#if __x86_64__
+#define SPECIFICS_RR(G) \
+  G(2,2) G(2,3) G(2,4) G(2,8) G(2,10) \
+  G(3,2) G(3,3) G(3,4) G(3,8) G(3,10) \
+  G(4,2) G(4,3) G(4,4) G(4,8) G(4,10) \
+  G(8,2) G(8,3) G(8,4) G(8,8) G(8,10) \
+  G(10,2) G(10,3) G(10,4) G(10,8) G(10,10)
+#else
+#define SPECIFICS_RR(G) \
+  G(2,2) G(2,3) G(2,4) G(2,8) \
+  G(3,2) G(3,3) G(3,4) G(3,8) \
+  G(4,2) G(4,3) G(4,4) G(4,8) \
+  G(8,2) G(8,3) G(8,4) G(8,8)
+#endif
+#endif
 
 #define IEEE_CLASS_R(XKIND) \
   elemental type(ieee_class_type) function ieee_class_a##XKIND(x); \
@@ -462,8 +509,10 @@ end function ieee_real_a##AKIND##_i##KKIND;
   interface ieee_real
     SPECIFICS_I(IEEE_REAL_I)
     SPECIFICS_R(IEEE_REAL_R)
+#if FLANG_SUPPORT_R16
     SPECIFICS_II(IEEE_REAL_II)
     SPECIFICS_RI(IEEE_REAL_RI)
+#endif
   end interface ieee_real
   public :: ieee_real
 #undef IEEE_REAL_I
diff --git a/flang/test/CMakeLists.txt b/flang/test/CMakeLists.txt
index 43ad1e3312b643..a18a5c6519eda4 100644
--- a/flang/test/CMakeLists.txt
+++ b/flang/test/CMakeLists.txt
@@ -11,6 +11,16 @@ llvm_canonicalize_cmake_booleans(
 
 set(FLANG_TOOLS_DIR ${FLANG_BINARY_DIR}/bin)
 
+# Check if 128-bit float computations can be done via long double
+check_cxx_source_compiles(
+  "#include <cfloat>
+   #if LDBL_MANT_DIG != 113
+   #error LDBL_MANT_DIG != 113
+   #endif
+   int main() { return 0; }
+  "
+  HAVE_LDBL_MANT_DIG_113)
+
 # FIXME In out-of-tree builds, "SHLIBDIR" is undefined and passing it to
 # `configure_lit_site_cfg` leads to a configuration error. This is currently
 # only required by plugins/examples, which are not supported in out-of-tree
diff --git a/flang/test/Evaluate/fold-out_of_range.f90 b/flang/test/Evaluate/fold-out_of_range.f90
index 5a9f900beb2d59..6360eee5322bb2 100644
--- a/flang/test/Evaluate/fold-out_of_range.f90
+++ b/flang/test/Evaluate/fold-out_of_range.f90
@@ -1,6 +1,7 @@
 ! RUN: %python %S/test_folding.py %s %flang_fc1 -pedantic -triple x86_64-unknown-linux-gnu
 ! UNSUPPORTED: system-windows
 ! REQUIRES: target=x86_64{{.*}}
+! REQUIRES: flang-supports-f128-math
 ! Tests folding of OUT_OF_RANGE().
 module m
   integer(1),  parameter :: i1v(*)  = [ -huge(1_1)  - 1_1,  huge(1_1) ]
diff --git a/flang/test/Evaluate/folding07.f90 b/flang/test/Evaluate/folding07.f90
index 3b6a99df388268..d51df7acf7b8a6 100644
--- a/flang/test/Evaluate/folding07.f90
+++ b/flang/test/Evaluate/folding07.f90
@@ -1,3 +1,4 @@
+! REQUIRES: flang-supports-f128-math
 ! RUN: %python %S/test_folding.py %s %flang_fc1
 ! Test numeric model inquiry intrinsics
 
diff --git a/flang/test/Lower/Intrinsics/ieee_class_queries.f90 b/flang/test/Lower/Intrinsics/ieee_class_queries.f90
index bb7787ea903e23..b2f9df83a902a0 100644
--- a/flang/test/Lower/Intrinsics/ieee_class_queries.f90
+++ b/flang/test/Lower/Intrinsics/ieee_class_queries.f90
@@ -1,3 +1,4 @@
+! REQUIRES: flang-supports-f128-math
 ! RUN: bbc -emit-fir -o - %s | FileCheck %s
 
   ! CHECK-LABEL: func @_QQmain
diff --git a/flang/test/Lower/Intrinsics/ieee_unordered.f90 b/flang/test/Lower/Intrinsics/ieee_unordered.f90
index a6146eff7f06e7..b7e81d53a2d750 100644
--- a/flang/test/Lower/Intrinsics/ieee_unordered.f90
+++ b/flang/test/Lower/Intrinsics/ieee_unordered.f90
@@ -1,3 +1,4 @@
+! REQUIRES: flang-supports-f128-math
 ! RUN: bbc -emit-fir -hlfir=false -o - %s | FileCheck %s
 
 ! CHECK-LABEL: func @_QQmain
diff --git a/flang/test/Lower/common-block.f90 b/flang/test/Lower/common-block.f90
index 94e61b8bcc33db..b5c1389df45d35 100644
--- a/flang/test/Lower/common-block.f90
+++ b/flang/test/Lower/common-block.f90
@@ -1,3 +1,4 @@
+! REQUIRES: flang-supports-f128-math
 ! RUN: bbc %s -o - | tco | FileCheck %s
 ! RUN: %flang -emit-llvm -S -mmlir -disable-external-name-interop %s -o - | FileCheck %s
 
@@ -78,4 +79,3 @@ subroutine s7()
   real(16) r16
   common /co1/ r16
 end subroutine
-
diff --git a/flang/test/Semantics/kinds03.f90 b/flang/test/Semantics/kinds03.f90
index 751d4a9ffa3cbb..a15a4a9baa7315 100644
--- a/flang/test/Semantics/kinds03.f90
+++ b/flang/test/Semantics/kinds03.f90
@@ -1,3 +1,4 @@
+! REQUIRES: flang-supports-f128-math
 ! RUN: %python %S/test_symbols.py %s %flang_fc1
  !DEF: /MainProgram1/ipdt DerivedType
  !DEF: /MainProgram1/ipdt/k TypeParam INTEGER(4)
diff --git a/flang/test/Semantics/modfile26.f90 b/flang/test/Semantics/modfile26.f90
index 09dc8b0954d633..9c5d0015d91631 100644
--- a/flang/test/Semantics/modfile26.f90
+++ b/flang/test/Semantics/modfile26.f90
@@ -1,3 +1,4 @@
+! REQUIRES: flang-supports-f128-math
 ! RUN: %python %S/test_modfile.py %s %flang_fc1
 ! Intrinsics SELECTED_INT_KIND, SELECTED_REAL_KIND, PRECISION, RANGE,
 ! RADIX, DIGITS
diff --git a/flang/test/Semantics/realkinds-aarch64-01.f90 b/flang/test/Semantics/realkinds-aarch64-01.f90
index e22920ff991e93..2520c0b84c0e67 100644
--- a/flang/test/Semantics/realkinds-aarch64-01.f90
+++ b/flang/test/Semantics/realkinds-aarch64-01.f90
@@ -1,4 +1,5 @@
 ! REQUIRES: aarch64-registered-target
+! REQUIRES: flang-supports-f128-math
 ! RUN: %python %S/test_modfile.py %s %flang_fc1 -triple aarch64-unknown-linux-gnu
 
 module m1
diff --git a/flang/test/lit.cfg.py b/flang/test/lit.cfg.py
index 37869e7e2ecd7e..4acbc0606d1977 100644
--- a/flang/test/lit.cfg.py
+++ b/flang/test/lit.cfg.py
@@ -216,8 +216,9 @@
 # Add features and substitutions to test F128 math support.
 # %f128-lib substitution may be used to generate check prefixes
 # for LIT tests checking for F128 library support.
-if config.flang_runtime_f128_math_lib:
+if config.flang_runtime_f128_math_lib or config.have_ldbl_mant_dig_113:
     config.available_features.add("flang-supports-f128-math")
+if config.flang_runtime_f128_math_lib:
     config.available_features.add(
         "flang-f128-math-lib-" + config.flang_runtime_f128_math_lib
     )
diff --git a/flang/test/lit.site.cfg.py.in b/flang/test/lit.site.cfg.py.in
index fe6186d7140713..d1a0ac763cf8a0 100644
--- a/flang/test/lit.site.cfg.py.in
+++ b/flang/test/lit.site.cfg.py.in
@@ -31,6 +31,7 @@ if "openmp" in "@LLVM_ENABLE_RUNTIMES@".lower().split(";"):
 else:
     config.openmp_module_dir = None
 config.flang_runtime_f128_math_lib = "@FLANG_RUNTIME_F128_MATH_LIB@"
+config.have_ldbl_mant_dig_113 = "@HAVE_LDBL_MANT_DIG_113@"
 
 import lit.llvm
 lit.llvm.initialize(lit_config, config)
diff --git a/flang/tools/f18/CMakeLists.txt b/flang/tools/f18/CMakeLists.txt
index cec4e2d8107206..344a781c41e957 100644
--- a/flang/tools/f18/CMakeLists.txt
+++ b/flang/tools/f18/CMakeLists.txt
@@ -31,6 +31,25 @@ set(MODULES_WITHOUT_IMPLEMENTATION
 
 set(MODULES ${MODULES_WITH_IMPLEMENTATION} ${MODULES_WITHOUT_IMPLEMENTATION})
 
+# Check if 128-bit float computations can be done via long double.
+check_cxx_source_compiles(
+  "#include <cfloat>
+   #if LDBL_MANT_DIG != 113
+   #error LDBL_MANT_DIG != 113
+   #endif
+   int main() { return 0; }
+  "
+  HAVE_LDBL_MANT_DIG_113)
+
+# Figure out whether we can support REAL(KIND=16)
+if (FLANG_RUNTIME_F128_MATH_LIB)
+  set(FLANG_SUPPORT_R16 "1")
+elseif (HAVE_LDBL_MANT_DIG_113)
+  set(FLANG_SUPPORT_R16 "1")
+else()
+  set(FLANG_SUPPORT_R16 "0")
+endif()
+
 # Init variable to hold extra object files coming from the Fortran modules;
 # these module files will be contributed from the CMakeLists in flang/tools/f18.
 set(module_objects "")
@@ -76,6 +95,10 @@ if (NOT CMAKE_CROSSCOMPILING)
       endif()
     endif()
 
+    set(decls "")
+    if (FLANG_SUPPORT_R16)
+      set(decls "-DFLANG_SUPPORT_R16")
+    endif()
 
     # Some modules have an implementation part that needs to be added to the
     # FortranRuntime library.
@@ -92,7 +115,7 @@ if (NOT CMAKE_CROSSCOMPILING)
     # TODO: We may need to flag this with conditional, in case Flang is built w/o OpenMP support
     add_custom_command(OUTPUT ${base}.mod ${object_output}
       COMMAND ${CMAKE_COMMAND} -E make_directory ${FLANG_INTRINSIC_MODULES_DIR}
-      COMMAND flang-new ${opts} -cpp ${compile_with} -module-dir ${FLANG_INTRINSIC_MODULES_DIR}
+      COMMAND flang-new ${opts} ${decls} -cpp ${compile_with} -module-dir ${FLANG_INTRINSIC_MODULES_DIR}
         ${FLANG_SOURCE_DIR}/module/${filename}.f90
       DEPENDS flang-new ${FLANG_SOURCE_DIR}/module/${filename}.f90 ${FLANG_SOURCE_DIR}/module/__fortran_builtins.f90 ${depends}
     )

psteinfeld · 2024-09-03T12:48:35Z

@tblah, thanks for including me among the reviewers. I've done a preliminary build and test, and I see many failures. But out internal builds are a little different from the standard build. So it's unclear what the cause of these failures it. It will take me a little while to analyze them. Please be patient and do not merge until I've had a chance to look more deeply into these failures.

psteinfeld

Thanks to help from Slava, I was able to fix up our local build and re-run all of the tests, and all looks good!

vzakhari · 2024-09-03T20:30:16Z

flang/include/flang/Tools/TargetSetup.h

+#ifdef FLANG_RUNTIME_F128_MATH_LIB
+  // we can use libquadmath wrappers
+  constexpr bool f128Support = true;
+#elif LDBL_MANT_DIG == 113


Ideally, this should be taken from the TargetInfo::getLongDoubleFormat(), so that f128Support does not depend on the host build compiler. I understand that there is no current use of TargetInfo in flang due to concerns about adding more dependencies on clang, but maybe we should put a TODO note here to clean it up later.

tblah · 2024-09-05T11:40:39Z

@vzakhari are you happy with this with the TODO message added in 67b1f42?

vzakhari · 2024-09-05T14:58:32Z

@vzakhari are you happy with this with the TODO message added in 67b1f42?

Thank you, Tom! Sorry for the delay.

[flang] Warn when F128 is unsupported (llvm#102147)

9588c75

This generates `warning: REAL(KIND=16) is not an enabled type for this target` if that type is used in a build not correctly configured to support this type. Uses of `selected_real_kind(30)` return -1.

tblah requested review from sscalpone, clementval, klausler, psteinfeld and vzakhari September 2, 2024 09:42

llvmbot added flang Flang issues not falling into any other category flang:fir-hlfir flang:semantics labels Sep 2, 2024

psteinfeld approved these changes Sep 3, 2024

View reviewed changes

vzakhari reviewed Sep 3, 2024

View reviewed changes

Add TODO message

67b1f42

vzakhari approved these changes Sep 5, 2024

View reviewed changes

tblah merged commit 3b19e48 into llvm:main Sep 5, 2024
8 checks passed

tblah mentioned this pull request Sep 26, 2024

[flang] Add flag to disable Float128 runtime #110116

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