fpu: Pass float_status to floatx80_is_infinity()

Unlike the other float formats, whether a floatx80 value is
considered to be an Infinity is target-dependent.  (On x86 if the
explicit integer bit is clear this is a "pseudo-infinity" and not a
valid infinity; m68k does not care about the value of the integer
bit.)

Currently we select this target-specific logic at compile time with
an ifdef.  We're going to want to do this at runtime, so change the
floatx80_is_infinity() function to take a float_status.

This commit doesn't change any logic; we'll do that in the
next commit.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250224111524.1101196-5-peter.maydell@linaro.org

3 files changed, 13 insertions, 11 deletions

diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h
index afae390602..3c83d703ba 100644
--- a/include/fpu/softfloat.h
+++ b/include/fpu/softfloat.h
@@ -996,7 +996,7 @@ static inline floatx80 floatx80_chs(floatx80 a)
     return a;
 }
 
-static inline bool floatx80_is_infinity(floatx80 a)
+static inline bool floatx80_is_infinity(floatx80 a, float_status *status)
 {
 #if defined(TARGET_M68K)
     return (a.high & 0x7fff) == floatx80_infinity.high && !(a.low << 1);
diff --git a/target/i386/tcg/fpu_helper.c b/target/i386/tcg/fpu_helper.c
index 741af09f90..3b79bc049d 100644
--- a/target/i386/tcg/fpu_helper.c
+++ b/target/i386/tcg/fpu_helper.c
@@ -1393,7 +1393,8 @@ void helper_fpatan(CPUX86State *env)
         /* Pass this NaN through.  */
     } else if (floatx80_is_zero(ST1) && !arg0_sign) {
         /* Pass this zero through.  */
-    } else if (((floatx80_is_infinity(ST0) && !floatx80_is_infinity(ST1)) ||
+    } else if (((floatx80_is_infinity(ST0, &env->fp_status) &&
+                 !floatx80_is_infinity(ST1, &env->fp_status)) ||
                  arg0_exp - arg1_exp >= 80) &&
                !arg0_sign) {
         /*
@@ -1442,8 +1443,8 @@ void helper_fpatan(CPUX86State *env)
             rexp = pi_exp;
             rsig0 = pi_sig_high;
             rsig1 = pi_sig_low;
-        } else if (floatx80_is_infinity(ST1)) {
-            if (floatx80_is_infinity(ST0)) {
+        } else if (floatx80_is_infinity(ST1, &env->fp_status)) {
+            if (floatx80_is_infinity(ST0, &env->fp_status)) {
                 if (arg0_sign) {
                     rexp = pi_34_exp;
                     rsig0 = pi_34_sig_high;
@@ -1462,7 +1463,8 @@ void helper_fpatan(CPUX86State *env)
             rexp = pi_2_exp;
             rsig0 = pi_2_sig_high;
             rsig1 = pi_2_sig_low;
-        } else if (floatx80_is_infinity(ST0) || arg0_exp - arg1_exp >= 80) {
+        } else if (floatx80_is_infinity(ST0, &env->fp_status) ||
+                   arg0_exp - arg1_exp >= 80) {
             /* ST0 is negative.  */
             rexp = pi_exp;
             rsig0 = pi_sig_high;
@@ -1829,7 +1831,7 @@ void helper_fxtract(CPUX86State *env)
         }
         fpush(env);
         ST0 = ST1;
-    } else if (floatx80_is_infinity(ST0)) {
+    } else if (floatx80_is_infinity(ST0, &env->fp_status)) {
         fpush(env);
         ST0 = ST1;
         ST1 = floatx80_default_inf(0, &env->fp_status);
@@ -2173,7 +2175,7 @@ void helper_fyl2x(CPUX86State *env)
     } else if (arg0_sign && !floatx80_is_zero(ST0)) {
         float_raise(float_flag_invalid, &env->fp_status);
         ST1 = floatx80_default_nan(&env->fp_status);
-    } else if (floatx80_is_infinity(ST1)) {
+    } else if (floatx80_is_infinity(ST1, &env->fp_status)) {
         FloatRelation cmp = floatx80_compare(ST0, floatx80_one,
                                              &env->fp_status);
         switch (cmp) {
@@ -2188,7 +2190,7 @@ void helper_fyl2x(CPUX86State *env)
             ST1 = floatx80_default_nan(&env->fp_status);
             break;
         }
-    } else if (floatx80_is_infinity(ST0)) {
+    } else if (floatx80_is_infinity(ST0, &env->fp_status)) {
         if (floatx80_is_zero(ST1)) {
             float_raise(float_flag_invalid, &env->fp_status);
             ST1 = floatx80_default_nan(&env->fp_status);
@@ -2341,11 +2343,11 @@ void helper_fscale(CPUX86State *env)
             float_raise(float_flag_invalid, &env->fp_status);
             ST0 = floatx80_silence_nan(ST0, &env->fp_status);
         }
-    } else if (floatx80_is_infinity(ST1) &&
+    } else if (floatx80_is_infinity(ST1, &env->fp_status) &&
                !floatx80_invalid_encoding(ST0) &&
                !floatx80_is_any_nan(ST0)) {
         if (floatx80_is_neg(ST1)) {
-            if (floatx80_is_infinity(ST0)) {
+            if (floatx80_is_infinity(ST0, &env->fp_status)) {
                 float_raise(float_flag_invalid, &env->fp_status);
                 ST0 = floatx80_default_nan(&env->fp_status);
             } else {
diff --git a/target/m68k/fpu_helper.c b/target/m68k/fpu_helper.c
index 339b73ad7d..eb1cb8c687 100644
--- a/target/m68k/fpu_helper.c
+++ b/target/m68k/fpu_helper.c
@@ -455,7 +455,7 @@ void HELPER(ftst)(CPUM68KState *env, FPReg *val)
 
     if (floatx80_is_any_nan(val->d)) {
         cc |= FPSR_CC_A;
-    } else if (floatx80_is_infinity(val->d)) {
+    } else if (floatx80_is_infinity(val->d, &env->fp_status)) {
         cc |= FPSR_CC_I;
     } else if (floatx80_is_zero(val->d)) {
         cc |= FPSR_CC_Z;