[PATCH] D49330: [compiler-rt] Include -lm when using compiler-rt, due to dependencies in some __div methods.

[Jordan Rupprecht via Phabricator via cfe-commits]

rupprecht added a comment.

Thanks Eli, I'll see how hard it is to remove those calls to logb/logbf (those 
seem to be the only ones causing link errors) and revert this change if that's 
possible.


Repository:
  rC Clang

https://reviews.llvm.org/D49330



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[PATCH] D49330: [compiler-rt] Include -lm when using compiler-rt, due to dependencies in some __div methods.

[Eli Friedman via Phabricator via cfe-commits]

efriedma added a comment.

Probably compiler-rt should be fixed so it doesn't need libm, rather than 
fixing clang to add -lm.  (All the functions it currently uses can be 
implemented with simple bit manipulation.)


Repository:
  rC Clang

https://reviews.llvm.org/D49330



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[PATCH] D49330: [compiler-rt] Include -lm when using compiler-rt, due to dependencies in some __div methods.

[Jordan Rupprecht via Phabricator via cfe-commits]

rupprecht created this revision.
rupprecht added a reviewer: saugustine.
Herald added subscribers: cfe-commits, aheejin, sbc100, dberris, srhines.

Some methods in compiler-rt builtins have dependencies on libm. Therefore 
building with -rtlib=compiler-rt is completely broken if those symbols are used 
and users don't include -lm themselves.

Fixes PR32279 and PR28652.


Repository:
  rC Clang

https://reviews.llvm.org/D49330

Files:
  lib/Driver/ToolChains/CommonArgs.cpp
  test/Driver/linux-ld.c
  test/Driver/wasm-toolchain.c
  test/Driver/wasm-toolchain.cpp


Index: test/Driver/wasm-toolchain.cpp
===
--- test/Driver/wasm-toolchain.cpp
+++ test/Driver/wasm-toolchain.cpp
@@ -14,10 +14,10 @@
 
 // RUN: %clangxx -### -no-canonical-prefixes -target wasm32-unknown-unknown 
--sysroot=/foo --stdlib=c++ %s 2>&1 | FileCheck -check-prefix=LINK %s
 // LINK: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
-// LINK: lld{{.*}}" "-flavor" "wasm" "-L/foo/lib" "crt1.o" "[[temp]]" "-lc++" 
"-lc++abi" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
+// LINK: lld{{.*}}" "-flavor" "wasm" "-L/foo/lib" "crt1.o" "[[temp]]" "-lc++" 
"-lc++abi" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-lm" "-o" "a.out"
 
 // A basic C++ link command-line with optimization.
 
 // RUN: %clangxx -### -O2 -no-canonical-prefixes -target 
wasm32-unknown-unknown --sysroot=/foo %s --stdlib=c++ 2>&1 | FileCheck 
-check-prefix=LINK_OPT %s
 // LINK_OPT: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
-// LINK_OPT: lld{{.*}}" "-flavor" "wasm" "-L/foo/lib" "crt1.o" "[[temp]]" 
"-lc++" "-lc++abi" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
+// LINK_OPT: lld{{.*}}" "-flavor" "wasm" "-L/foo/lib" "crt1.o" "[[temp]]" 
"-lc++" "-lc++abi" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-lm" "-o" 
"a.out"
Index: test/Driver/wasm-toolchain.c
===
--- test/Driver/wasm-toolchain.c
+++ test/Driver/wasm-toolchain.c
@@ -14,10 +14,10 @@
 
 // RUN: %clang -### -no-canonical-prefixes -target wasm32-unknown-unknown 
--sysroot=/foo %s 2>&1 | FileCheck -check-prefix=LINK %s
 // LINK: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
-// LINK: lld{{.*}}" "-flavor" "wasm" "-L/foo/lib" "crt1.o" "[[temp]]" "-lc" 
"{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
+// LINK: lld{{.*}}" "-flavor" "wasm" "-L/foo/lib" "crt1.o" "[[temp]]" "-lc" 
"{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-lm" "-o" "a.out"
 
 // A basic C link command-line with optimization.
 
 // RUN: %clang -### -O2 -no-canonical-prefixes -target wasm32-unknown-unknown 
--sysroot=/foo %s 2>&1 | FileCheck -check-prefix=LINK_OPT %s
 // LINK_OPT: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
-// LINK_OPT: lld{{.*}}" "-flavor" "wasm" "-L/foo/lib" "crt1.o" "[[temp]]" 
"-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
+// LINK_OPT: lld{{.*}}" "-flavor" "wasm" "-L/foo/lib" "crt1.o" "[[temp]]" 
"-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-lm" "-o" "a.out"
Index: test/Driver/linux-ld.c
===
--- test/Driver/linux-ld.c
+++ test/Driver/linux-ld.c
@@ -67,8 +67,10 @@
 // CHECK-LD-RT: "-L[[SYSROOT]]/lib"
 // CHECK-LD-RT: "-L[[SYSROOT]]/usr/lib"
 // CHECK-LD-RT: libclang_rt.builtins-x86_64.a"
+// CHECK-LD-RT: "-lm"
 // CHECK-LD-RT: "-lc"
 // CHECK-LD-RT: libclang_rt.builtins-x86_64.a"
+// CHECK-LD-RT: "-lm"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN: --target=i686-unknown-linux \
@@ -88,8 +90,10 @@
 // CHECK-LD-RT-I686: "-L[[SYSROOT]]/lib"
 // CHECK-LD-RT-I686: "-L[[SYSROOT]]/usr/lib"
 // CHECK-LD-RT-I686: libclang_rt.builtins-i386.a"
+// CHECK-LD-RT-I686: "-lm"
 // CHECK-LD-RT-I686: "-lc"
 // CHECK-LD-RT-I686: libclang_rt.builtins-i386.a"
+// CHECK-LD-RT-I686: "-lm"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN: --target=arm-linux-androideabi \
@@ -103,8 +107,10 @@
 // CHECK-LD-RT-ANDROID: "-m" "armelf_linux_eabi"
 // CHECK-LD-RT-ANDROID: "-dynamic-linker"
 // CHECK-LD-RT-ANDROID: libclang_rt.builtins-arm-android.a"
+// CHECK-LD-RT-ANDROID: "-lm"
 // CHECK-LD-RT-ANDROID: "-lc"
 // CHECK-LD-RT-ANDROID: libclang_rt.builtins-arm-android.a"
+// CHECK-LD-RT-ANDROID: "-lm"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN: --target=x86_64-unknown-linux -rtlib=platform \
Index: lib/Driver/ToolChains/CommonArgs.cpp
===
--- lib/Driver/ToolChains/CommonArgs.cpp
+++ lib/Driver/ToolChains/CommonArgs.cpp
@@ -1162,6 +1162,8 @@
   switch (RLT) {
   case ToolChain::RLT_CompilerRT:
 CmdArgs.push_back(TC.getCompilerRTArgString(Args, "builtins"));
+// Some methods such as __divdc3, __divsc3, and __divxc3 rely on libm
+CmdArgs.push_back("-lm");
 break;
   case ToolChain::RLT_Libgcc:
 // Make sure libgcc is not used under