clang generates mismatching wasm compiler-rt function signatures with -mmulti-value

[TerrorJack]

When -mmulti-value is added in wasi-sdk (the wasi-libc CFLAGS, and all CMAKE_C_FLAGS & CMAKE_CXX_FLAGS in the top-level makefile), clang generates mismatching wasm compiler-rt function signatures, as can be seen in the wasm-ld warning messages:

wasm-ld: warning: function signature mismatch: __udivti3
>>> defined as (i32, i64, i64, i64, i64) -> void in /home/gitpod/.ghc-wasm/wasi-sdk/lib/clang/15.0.5/lib/wasi/libclang_rt.builtins-wasm32.a(muloti4.c.obj)
>>> defined as (i64, i64, i64, i64) -> i64 in /home/gitpod/.ghc-wasm/wasi-sdk/lib/clang/15.0.5/lib/wasi/libclang_rt.builtins-wasm32.a(udivti3.c.obj)

wasm-ld: warning: function signature mismatch: __multi3
>>> defined as (i32, i64, i64, i64, i64) -> void in /home/gitpod/.ghc-wasm/wasi-sdk/bin/../share/wasi-sysroot/lib/wasm32-wasi/libc.a(intscan.o)
>>> defined as (i64, i64, i64, i64) -> i64 in /home/gitpod/.ghc-wasm/wasi-sdk/lib/clang/15.0.5/lib/wasi/libclang_rt.builtins-wasm32.a(multi3.c.obj)

wasm-ld: warning: function signature mismatch: __muloti4
>>> defined as (i32, i64, i64, i64, i64, i32) -> void in /home/gitpod/.ghc-wasm/wasi-sdk/bin/../share/wasi-sysroot/lib/wasm32-wasi/libc.a(pselect.o)
>>> defined as (i64, i64, i64, i64, i32) -> i64 in /home/gitpod/.ghc-wasm/wasi-sdk/lib/clang/15.0.5/lib/wasi/libclang_rt.builtins-wasm32.a(muloti4.c.obj)

Posting the bug early, and a self-contained minimal repro should come later.

[llvmbot]

@llvm/issue-subscribers-backend-webassembly

[TerrorJack]

Hi folks, I came up with the minimum repro that works for latest clang-15 official apt release on ubuntu-22.04:

Content of muloti4.c (preprocessed & shrinked from https://github.com/llvm/llvm-project/blob/release/15.x/compiler-rt/lib/builtins/muloti4.c):

a, c;
__int128 b;
fn1() {
  if (b < 0)
    if (a > 8 / b)
      c = 0;
}

Content of udivti3.c (preprocessed from https://github.com/llvm/llvm-project/blob/release/15.x/compiler-rt/lib/builtins/udivti3.c):

# 1 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/udivti3.c"
# 1 "<built-in>" 1
# 1 "<built-in>" 3
# 327 "<built-in>" 3
# 1 "<command line>" 1
# 1 "<built-in>" 2
# 1 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/udivti3.c" 2
# 13 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/udivti3.c"
# 1 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_lib.h" 1
# 92 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_lib.h"
# 1 "/usr/lib/llvm-15/lib/clang/15.0.6/include/float.h" 1 3
# 93 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_lib.h" 2
# 1 "/usr/lib/llvm-15/lib/clang/15.0.6/include/limits.h" 1 3
# 21 "/usr/lib/llvm-15/lib/clang/15.0.6/include/limits.h" 3
# 1 "/tmp/wasi-sysroot/include/limits.h" 1 3



# 1 "/tmp/wasi-sysroot/include/features.h" 1 3
# 5 "/tmp/wasi-sysroot/include/limits.h" 2 3

# 1 "/tmp/wasi-sysroot/include/bits/alltypes.h" 1 3
# 269 "/tmp/wasi-sysroot/include/bits/alltypes.h" 3
# 1 "/tmp/wasi-sysroot/include/__struct_timeval.h" 1 3



# 1 "/tmp/wasi-sysroot/include/__typedef_time_t.h" 1 3




typedef long long time_t;
# 5 "/tmp/wasi-sysroot/include/__struct_timeval.h" 2 3
# 1 "/tmp/wasi-sysroot/include/__typedef_suseconds_t.h" 1 3





typedef long long suseconds_t;
# 6 "/tmp/wasi-sysroot/include/__struct_timeval.h" 2 3


struct timeval {
    time_t tv_sec;
    suseconds_t tv_usec;
};
# 270 "/tmp/wasi-sysroot/include/bits/alltypes.h" 2 3
# 1 "/tmp/wasi-sysroot/include/__struct_timespec.h" 1 3






struct timespec {
    time_t tv_sec;
    long tv_nsec;
};
# 271 "/tmp/wasi-sysroot/include/bits/alltypes.h" 2 3
# 402 "/tmp/wasi-sysroot/include/bits/alltypes.h" 3
# 1 "/tmp/wasi-sysroot/include/__struct_iovec.h" 1 3




# 1 "/usr/lib/llvm-15/lib/clang/15.0.6/include/stddef.h" 1 3
# 46 "/usr/lib/llvm-15/lib/clang/15.0.6/include/stddef.h" 3
typedef long unsigned int size_t;
# 6 "/tmp/wasi-sysroot/include/__struct_iovec.h" 2 3

struct iovec {
    void *iov_base;
    size_t iov_len;
};
# 403 "/tmp/wasi-sysroot/include/bits/alltypes.h" 2 3
# 7 "/tmp/wasi-sysroot/include/limits.h" 2 3
# 40 "/tmp/wasi-sysroot/include/limits.h" 3
# 1 "/tmp/wasi-sysroot/include/bits/limits.h" 1 3
# 1 "/tmp/wasi-sysroot/include/__macro_PAGESIZE.h" 1 3
# 2 "/tmp/wasi-sysroot/include/bits/limits.h" 2 3
# 41 "/tmp/wasi-sysroot/include/limits.h" 2 3
# 22 "/usr/lib/llvm-15/lib/clang/15.0.6/include/limits.h" 2 3
# 94 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_lib.h" 2
# 1 "/usr/lib/llvm-15/lib/clang/15.0.6/include/stdbool.h" 1 3
# 95 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_lib.h" 2
# 1 "/usr/lib/llvm-15/lib/clang/15.0.6/include/stdint.h" 1 3
# 52 "/usr/lib/llvm-15/lib/clang/15.0.6/include/stdint.h" 3
# 1 "/tmp/wasi-sysroot/include/stdint.h" 1 3
# 20 "/tmp/wasi-sysroot/include/stdint.h" 3
# 1 "/tmp/wasi-sysroot/include/bits/alltypes.h" 1 3
# 77 "/tmp/wasi-sysroot/include/bits/alltypes.h" 3
typedef unsigned long uintptr_t;
# 92 "/tmp/wasi-sysroot/include/bits/alltypes.h" 3
typedef long intptr_t;
# 130 "/tmp/wasi-sysroot/include/bits/alltypes.h" 3
typedef signed char int8_t;




typedef signed short int16_t;




typedef signed int int32_t;




typedef signed long long int64_t;




typedef signed long long intmax_t;




typedef unsigned char uint8_t;




typedef unsigned short uint16_t;




typedef unsigned int uint32_t;




typedef unsigned long long uint64_t;
# 180 "/tmp/wasi-sysroot/include/bits/alltypes.h" 3
typedef unsigned long long uintmax_t;
# 21 "/tmp/wasi-sysroot/include/stdint.h" 2 3

typedef int8_t int_fast8_t;
typedef int64_t int_fast64_t;

typedef int8_t int_least8_t;
typedef int16_t int_least16_t;
typedef int32_t int_least32_t;
typedef int64_t int_least64_t;

typedef uint8_t uint_fast8_t;
typedef uint64_t uint_fast64_t;

typedef uint8_t uint_least8_t;
typedef uint16_t uint_least16_t;
typedef uint32_t uint_least32_t;
typedef uint64_t uint_least64_t;
# 95 "/tmp/wasi-sysroot/include/stdint.h" 3
# 1 "/tmp/wasi-sysroot/include/bits/stdint.h" 1 3
typedef int16_t int_fast16_t;
typedef int32_t int_fast32_t;
typedef uint16_t uint_fast16_t;
typedef uint32_t uint_fast32_t;
# 96 "/tmp/wasi-sysroot/include/stdint.h" 2 3
# 53 "/usr/lib/llvm-15/lib/clang/15.0.6/include/stdint.h" 2 3
# 96 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_lib.h" 2



# 1 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_types.h" 1
# 19 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_types.h"
# 1 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_endianness.h" 1
# 20 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_types.h" 2





typedef int32_t si_int;
typedef uint32_t su_int;
# 37 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_types.h"
typedef int64_t di_int;
typedef uint64_t du_int;

typedef union {
  di_int all;
  struct {

    su_int low;
    si_int high;




  } s;
} dwords;

typedef union {
  du_int all;
  struct {

    su_int low;
    su_int high;




  } s;
} udwords;
# 79 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_types.h"
typedef int ti_int __attribute__((mode(TI)));
typedef unsigned tu_int __attribute__((mode(TI)));

typedef union {
  ti_int all;
  struct {

    du_int low;
    di_int high;




  } s;
} twords;

typedef union {
  tu_int all;
  struct {

    du_int low;
    du_int high;




  } s;
} utwords;

static inline ti_int make_ti(di_int h, di_int l) {
  twords r;
  r.s.high = h;
  r.s.low = l;
  return r.all;
}

static inline tu_int make_tu(du_int h, du_int l) {
  utwords r;
  r.s.high = h;
  r.s.low = l;
  return r.all;
}
# 133 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_types.h"
typedef union {
  su_int u;
  float f;
} float_bits;

typedef union {
  udwords u;
  double f;
} double_bits;


typedef struct {

  udwords low;
  udwords high;




} uqwords;
# 169 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_types.h"
typedef union {
  uqwords u;
  long double f;
} long_double_bits;


typedef float _Complex Fcomplex;
typedef double _Complex Dcomplex;
typedef long double _Complex Lcomplex;
# 100 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_lib.h" 2


# 1 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_util.h" 1
# 23 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_util.h"
__attribute__((noreturn)) void __compilerrt_abort_impl(const char *file, int line,
                                      const char *function);
# 103 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/int_lib.h" 2

                int __paritysi2(si_int a);
                int __paritydi2(di_int a);

                di_int __divdi3(di_int a, di_int b);
                si_int __divsi3(si_int a, si_int b);
                su_int __udivsi3(su_int n, su_int d);

                su_int __udivmodsi4(su_int a, su_int b, su_int *rem);
                du_int __udivmoddi4(du_int a, du_int b, du_int *rem);

                int __clzti2(ti_int a);
                tu_int __udivmodti4(tu_int a, tu_int b, tu_int *rem);
# 14 "/workspace/wasi-sdk/src/llvm-project/compiler-rt/lib/builtins/udivti3.c" 2





                tu_int __udivti3(tu_int a, tu_int b) {
  return __udivmodti4(a, b, 0);
}

The command to compile and reproduce:

clang-15 --target=wasm32 -mmultivalue -O2 -o muloti4.c.obj -c muloti4.c
clang-15 --target=wasm32 -mmultivalue -o udivti3.c.obj -c udivti3.c
wasm-ld-15 -r muloti4.c.obj udivti3.c.obj -o combined.o

You can see the warning message about signature mismatch when -mmultivalue is enabled:

wasm-ld: warning: function signature mismatch: __udivti3
>>> defined as (i32, i64, i64, i64, i64) -> void in muloti4.c.obj
>>> defined as (i64, i64, i64, i64) -> i64 in udivti3.c.obj

I hope the example above helps in looking into this issue, thanks :)

[HerrCai0907]

canditate D146271

[TerrorJack]

@HerrCai0907 Thanks a lot for D146271! I tried cherry-picking it on top of 16.0.0 in my fork, enabling -mmultivalue in sysroot of wasi-sdk, then the test suite produced the following warnings and errors:

Testing printf-long-double-enabled.c...
Testing printf-long-double-enabled.c...
wasm-ld: warning: function signature mismatch: __subtf3
>>> defined as (i32, i64, i64, i64, i64) -> void in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/share/wasi-sysroot/lib/wasm32-wasi/libc-printscan-long-double.a(vfprintf.long-double.o)
>>> defined as (i64, i64, i64, i64) -> i64 in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/16/lib/wasi/libclang_rt.builtins-wasm32.a(subtf3.c.obj)

wasm-ld: warning: function signature mismatch: __addtf3
>>> defined as (i32, i64, i64, i64, i64) -> void in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/share/wasi-sysroot/lib/wasm32-wasi/libc-printscan-long-double.a(vfprintf.long-double.o)
>>> defined as (i64, i64, i64, i64) -> i64 in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/16/lib/wasi/libclang_rt.builtins-wasm32.a(addtf3.c.obj)

wasm-ld: warning: function signature mismatch: __ashlti3
>>> defined as (i64, i64, i32) -> i64 in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/16/lib/wasi/libclang_rt.builtins-wasm32.a(addtf3.c.obj)
>>> defined as (i64, i64, i32) -> i64 in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/16/lib/wasi/libclang_rt.builtins-wasm32.a(ashlti3.c.obj)

wasm-ld: warning: function signature mismatch: __floatunsitf
>>> defined as (i32, i32) -> void in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/share/wasi-sysroot/lib/wasm32-wasi/libc-printscan-long-double.a(vfprintf.long-double.o)
>>> defined as (i32) -> i64 in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/16/lib/wasi/libclang_rt.builtins-wasm32.a(floatunsitf.c.obj)

wasm-ld: warning: function signature mismatch: __extenddftf2
>>> defined as (i32, f64) -> void in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/share/wasi-sysroot/lib/wasm32-wasi/libc-printscan-long-double.a(vfprintf.long-double.o)
>>> defined as (f64) -> i64 in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/16/lib/wasi/libclang_rt.builtins-wasm32.a(extenddftf2.c.obj)

wasm-ld: warning: function signature mismatch: __lshrti3
>>> defined as (i64, i64, i32) -> i64 in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/16/lib/wasi/libclang_rt.builtins-wasm32.a(addtf3.c.obj)
>>> defined as (i64, i64, i32) -> i64 in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/16/lib/wasi/libclang_rt.builtins-wasm32.a(lshrti3.c.obj)

wasm-ld: warning: function signature mismatch: __multf3
>>> defined as (i32, i64, i64, i64, i64) -> void in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/share/wasi-sysroot/lib/wasm32-wasi/libc.a(frexpl.o)
>>> defined as (i64, i64, i64, i64) -> i64 in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/16/lib/wasi/libclang_rt.builtins-wasm32.a(multf3.c.obj)

wasm-ld: warning: function signature mismatch: __floatsitf
>>> defined as (i32, i32) -> void in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/share/wasi-sysroot/lib/wasm32-wasi/libc-printscan-long-double.a(vfprintf.long-double.o)
>>> defined as (i32) -> i64 in /builds/ghc/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/16/lib/wasi/libclang_rt.builtins-wasm32.a(floatsitf.c.obj)
--- /dev/null
+++ printf-long-double-enabled.c.-O0.stderr.observed
@@ -0,0 +1,6 @@
+Error: failed to run main module `printf-long-double-enabled.c.-O0.wasm`
+
+Caused by:
+    0: failed to compile wasm function 36 (`pop_arg`) at offset 0x209e
+    1: WebAssembly translation error
+    2: Invalid input WebAssembly code at offset 8900: type mismatch: expected i32 but nothing on stack
make: *** [Makefile:48: check] Error 1

So it seems there are still some cases not covered by that patch. I'll try to come up with a more self-contained repro soon.

[TerrorJack]

Here's a minimal repro for the signature mismatch of __subtf3, after applying D146271 on 16.0.0:

int a;
long double b;
int fn1() {
  a -= b;
  return 0;
}

$ build/install/opt/wasi-sdk/bin/clang -mmultivalue --target=wasm32-wasi -S -o floatscan.long-double.s floatscan.long-double.c

The above command would generate a call to __subtf3 with signature (i32, i64, i64, i64, i64) -> (), even if -mmultivalue has been passed.

long double __subtf3(long double, long double) {}

build/install/opt/wasi-sdk/bin/clang --target=wasm32-wasi -mmultivalue -o subtf3.s -S subtf3.c

The above command that compiles __subtf3 will generate a __subtf3 function with signature (i64, i64, i64, i64) -> (i64, i64). Which indeed is the expected behavior when -mmultivalue is enabled.

[HerrCai0907]

It's caused by this code Table[RTLIB::SUB_F128] = func_iPTR_i64_i64_i64_i64;
Let me check the implement of those code.

[HerrCai0907]

merge D146271.
fix long double in D146499

[TerrorJack]

@HerrCai0907 Thanks a lot for the two patches! I tried applying both D146271 and D146499 on top of 16.0.0, and now I have another minimum repro for a signature mismatch of __lshrti3:

__uint128_t toRep();
void fromRep() {
  __uint128_t bRep = toRep(), bSignificand = bRep;
  int align = bRep;
  bSignificand = bSignificand >> align;
  if (bSignificand)
    fromRep();
}

$ build/install/opt/wasi-sdk/bin/clang --target=wasm32 -mmultivalue -o addtf3.s -S addtf3.c
$ grep -F '.functype	__lshrti3 (i64, i64, i32) -> (i64, i64, i64, i64)' addtf3.s

__int128 __lshrti3(__int128, int) {}

$ build/install/opt/wasi-sdk/bin/clang --target=wasm32 -mmultivalue -o lshrti3.s -S lshrti3.c
$ grep -F '.functype	__lshrti3 (i64, i64, i32) -> (i64, i64)' lshrti3.s