[compiler-rt] r243746 - Fix __floatsitf() for negative input

[Sergey Dmitrouk]

Author: sdmitrouk
Date: Fri Jul 31 08:32:09 2015
New Revision: 243746

URL: http://llvm.org/viewvc/llvm-project?rev=243746&view=rev
Log:
Fix __floatsitf() for negative input

Negative numbers were handled properly initially, but got broken
during addressing review, so none of them did actually work.  Issues:
 * Wrong negation.
 * Wrong exponent calculation.

Modified:
    compiler-rt/trunk/lib/builtins/floatsitf.c
    compiler-rt/trunk/test/builtins/Unit/floatsitf_test.c

Modified: compiler-rt/trunk/lib/builtins/floatsitf.c
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/builtins/floatsitf.c?rev=243746&r1=243745&r2=243746&view=diff
==============================================================================
--- compiler-rt/trunk/lib/builtins/floatsitf.c (original)
+++ compiler-rt/trunk/lib/builtins/floatsitf.c Fri Jul 31 08:32:09 2015
@@ -30,16 +30,14 @@ COMPILER_RT_ABI fp_t __floatsitf(int a)
     unsigned aAbs = (unsigned)a;
     if (a < 0) {
         sign = signBit;
-        aAbs += 0x80000000;
+        aAbs = ~(unsigned)a + 1U;
     }
 
     // Exponent of (fp_t)a is the width of abs(a).
-    const int exponent = (aWidth - 1) - __builtin_clz(a);
+    const int exponent = (aWidth - 1) - __builtin_clz(aAbs);
     rep_t result;
 
-    // Shift a into the significand field and clear the implicit bit.  Extra
-    // cast to unsigned int is necessary to get the correct behavior for
-    // the input INT_MIN.
+    // Shift a into the significand field and clear the implicit bit.
     const int shift = significandBits - exponent;
     result = (rep_t)aAbs << shift ^ implicitBit;
 

Modified: compiler-rt/trunk/test/builtins/Unit/floatsitf_test.c
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/builtins/Unit/floatsitf_test.c?rev=243746&r1=243745&r2=243746&view=diff
==============================================================================
--- compiler-rt/trunk/test/builtins/Unit/floatsitf_test.c (original)
+++ compiler-rt/trunk/test/builtins/Unit/floatsitf_test.c Fri Jul 31 08:32:09 2015
@@ -40,6 +40,8 @@ char assumption_1[sizeof(long double) *
 int main()
 {
 #if __LDBL_MANT_DIG__ == 113
+    if (test__floatsitf(0x80000000, UINT64_C(0xc01e000000000000), UINT64_C(0x0)))
+        return 1;
     if (test__floatsitf(0x7fffffff, UINT64_C(0x401dfffffffc0000), UINT64_C(0x0)))
         return 1;
     if (test__floatsitf(0, UINT64_C(0x0), UINT64_C(0x0)))