diff --git a/docs/envvars.rst b/docs/envvars.rst
index f032c1ba2c7..a8dcc8c465c 100644
--- a/docs/envvars.rst
+++ b/docs/envvars.rst
@@ -1869,6 +1869,13 @@ r300 driver environment variables
       Disable AA compression and fast AA clear
    ``notcl``
       Disable hardware accelerated Transform/Clip/Lighting
+   ``ieeemath``
+      Force IEEE versions of VS math opcodes where applicable
+      and also IEEE handling of multiply by zero (R5xx only)
+   ``ffmath``
+      Force FF versions of VS math opcodes where applicable
+      and 0 * anything = 0 rules in FS
+
 
 Asahi driver environment variables
 ----------------------------------
diff --git a/src/gallium/drivers/r300/compiler/r3xx_vertprog.c b/src/gallium/drivers/r300/compiler/r3xx_vertprog.c
index e522fcae614..ff954b4e815 100644
--- a/src/gallium/drivers/r300/compiler/r3xx_vertprog.c
+++ b/src/gallium/drivers/r300/compiler/r3xx_vertprog.c
@@ -197,6 +197,26 @@ ei_math1(struct r300_vertex_program_code *vp, unsigned int hw_opcode,
    inst[3] = __CONST(0, RC_SWIZZLE_ZERO);
 }
 
+static void
+ei_math1_select(struct r300_vertex_program_code *vp,
+                unsigned math_mode,
+                unsigned hw_opcode_ieee,
+                unsigned hw_opcode_dx,
+                unsigned hw_opcode_ff,
+                struct rc_sub_instruction *vpi,
+                unsigned int *inst)
+{
+   unsigned hw_opcode;
+   switch (math_mode) {
+   case RC_MATH_IEEE: hw_opcode = hw_opcode_ieee; break;
+   case RC_MATH_DX: hw_opcode = hw_opcode_dx; break;
+   case RC_MATH_FF: hw_opcode = hw_opcode_ff; break;
+   default:
+      unreachable();
+   }
+   ei_math1(vp, hw_opcode, vpi, inst);
+}
+
 static void
 ei_cmp(struct r300_vertex_program_code *vp, struct rc_sub_instruction *vpi, unsigned int *inst)
 {
@@ -407,7 +427,8 @@ translate_vertex_program(struct radeon_compiler *c, void *user)
          ei_vector1(compiler->code, VE_FRACTION, vpi, inst);
          break;
       case RC_OPCODE_LG2:
-         ei_math1(compiler->code, ME_LOG_BASE2_FULL_DX, vpi, inst);
+         ei_math1_select(compiler->code, compiler->Base.math_rules, ME_LOG_BASE2_IEEE,
+                         ME_LOG_BASE2_FULL_DX, ME_LOG_BASE2_FULL_DX, vpi, inst);
          break;
       case RC_OPCODE_LIT:
          ei_lit(compiler->code, vpi, inst);
@@ -434,10 +455,12 @@ translate_vertex_program(struct radeon_compiler *c, void *user)
          ei_pow(compiler->code, vpi, inst);
          break;
       case RC_OPCODE_RCP:
-         ei_math1(compiler->code, ME_RECIP_DX, vpi, inst);
+         ei_math1_select(compiler->code, compiler->Base.math_rules, ME_RECIP_IEEE,
+                         ME_RECIP_DX, ME_RECIP_FF, vpi, inst);
          break;
       case RC_OPCODE_RSQ:
-         ei_math1(compiler->code, ME_RECIP_SQRT_DX, vpi, inst);
+         ei_math1_select(compiler->code, compiler->Base.math_rules, ME_RECIP_SQRT_IEEE,
+                         ME_RECIP_SQRT_DX, ME_RECIP_SQRT_FF, vpi, inst);
          break;
       case RC_OPCODE_SEQ:
          ei_vector2(compiler->code, VE_SET_EQUAL, vpi, inst);
diff --git a/src/gallium/drivers/r300/compiler/radeon_compiler.h b/src/gallium/drivers/r300/compiler/radeon_compiler.h
index 699500d1d35..f02b9551801 100644
--- a/src/gallium/drivers/r300/compiler/radeon_compiler.h
+++ b/src/gallium/drivers/r300/compiler/radeon_compiler.h
@@ -14,6 +14,10 @@
 
 #define RC_DBG_LOG (1 << 0)
 
+#define RC_MATH_DX        0x00
+#define RC_MATH_IEEE      0x01
+#define RC_MATH_FF        0x02
+
 struct rc_swizzle_caps;
 
 enum rc_program_type { RC_VERTEX_PROGRAM, RC_FRAGMENT_PROGRAM, RC_NUM_PROGRAM_TYPES };
@@ -45,6 +49,9 @@ struct radeon_compiler {
    /* Whether to remove unused constants and empty holes in constant space. */
    unsigned remove_unused_constants : 1;
 
+   /* Math compatibility mode, for some PVS opcodes and for multiply by zero rules on R5xx */
+   unsigned math_rules : 2;
+
    /**
     * Variables used internally, not be touched by callers
     * of the compiler
diff --git a/src/gallium/drivers/r300/r300_debug.c b/src/gallium/drivers/r300/r300_debug.c
index 8af57945716..1fe1eab0772 100644
--- a/src/gallium/drivers/r300/r300_debug.c
+++ b/src/gallium/drivers/r300/r300_debug.c
@@ -34,6 +34,8 @@ static const struct debug_named_value r300_debug_options[] = {
     { "nohiz", DBG_NO_HIZ, "Disable hierarchical zbuffer" },
     { "nocmask", DBG_NO_CMASK, "Disable AA compression and fast AA clear" },
     { "notcl", DBG_NO_TCL, "Disable hardware accelerated Transform/Clip/Lighting" },
+    { "ieeemath", DBG_IEEEMATH, "Force IEEE versions of VS math opcodes where applicable and also IEEE handling of multiply by zero (R5xx only)" },
+    { "ffmath", DBG_FFMATH, "Force FF versions of VS math opcodes where applicable and 0*anything=0 rules in FS" },
 
     /* must be last */
     DEBUG_NAMED_VALUE_END
diff --git a/src/gallium/drivers/r300/r300_debug_options.h b/src/gallium/drivers/r300/r300_debug_options.h
index 13f5aad8677..d43e7eea149 100644
--- a/src/gallium/drivers/r300/r300_debug_options.h
+++ b/src/gallium/drivers/r300/r300_debug_options.h
@@ -1,4 +1,6 @@
 OPT_BOOL(nohiz, false, "Disable hierarchical zbuffer")
 OPT_BOOL(nozmask, false, "Disable zbuffer compression")
+OPT_BOOL(ieeemath, false, "Force IEEE math rules and opcodes where applicable")
+OPT_BOOL(ffmath, false, "Force FF math rules and opcodes where applicable")
 
 #undef OPT_BOOL
diff --git a/src/gallium/drivers/r300/r300_fs.c b/src/gallium/drivers/r300/r300_fs.c
index fd39caa7368..3933274c238 100644
--- a/src/gallium/drivers/r300/r300_fs.c
+++ b/src/gallium/drivers/r300/r300_fs.c
@@ -255,7 +255,10 @@ static void r300_emit_fs_code_to_buffer(
                                code->int_constant_count * 2;
 
         NEW_CB(shader->cb_code, shader->cb_code_size);
-        OUT_CB_REG(R500_US_CONFIG, R500_ZERO_TIMES_ANYTHING_EQUALS_ZERO);
+        if (r300->screen->options.ieeemath)
+            OUT_CB_REG(R500_US_CONFIG, R500_ZERO_TIMES_ANYTHING_EQUALS_ZERO_DEFAULT);
+        else
+            OUT_CB_REG(R500_US_CONFIG, R500_ZERO_TIMES_ANYTHING_EQUALS_ZERO_LEGACY);
         OUT_CB_REG(R500_US_PIXSIZE, code->max_temp_idx);
         OUT_CB_REG(R500_US_FC_CTRL, code->us_fc_ctrl);
         for(i = 0; i < code->int_constant_count; i++){
diff --git a/src/gallium/drivers/r300/r300_reg.h b/src/gallium/drivers/r300/r300_reg.h
index 7b14a276912..25bbc69e232 100644
--- a/src/gallium/drivers/r300/r300_reg.h
+++ b/src/gallium/drivers/r300/r300_reg.h
@@ -3279,7 +3279,8 @@ enum {
 #   define R500_US_CODE_RANGE_ADDR(x)			((x) << 0)
 #   define R500_US_CODE_RANGE_SIZE(x)			((x) << 16)
 #define R500_US_CONFIG					0x4600
-#   define R500_ZERO_TIMES_ANYTHING_EQUALS_ZERO		(1 << 1)
+#   define R500_ZERO_TIMES_ANYTHING_EQUALS_ZERO_DEFAULT	(0 << 1)
+#   define R500_ZERO_TIMES_ANYTHING_EQUALS_ZERO_LEGACY	(1 << 1)
 #define R500_US_FC_ADDR_0				0xa000
 #   define R500_FC_BOOL_ADDR(x)				((x) << 0)
 #   define R500_FC_INT_ADDR(x)				((x) << 8)
diff --git a/src/gallium/drivers/r300/r300_screen.c b/src/gallium/drivers/r300/r300_screen.c
index 0f04489b3b1..c136dce8ac8 100644
--- a/src/gallium/drivers/r300/r300_screen.c
+++ b/src/gallium/drivers/r300/r300_screen.c
@@ -840,6 +840,11 @@ struct pipe_screen* r300_screen_create(struct radeon_winsys *rws,
     if (SCREEN_DBG_ON(r300screen, DBG_NO_TCL))
         r300screen->caps.has_tcl = false;
 
+    if (SCREEN_DBG_ON(r300screen, DBG_IEEEMATH))
+        r300screen->options.ieeemath = true;
+    if (SCREEN_DBG_ON(r300screen, DBG_FFMATH))
+        r300screen->options.ffmath = true;
+
     r300screen->rws = rws;
     r300screen->screen.destroy = r300_destroy_screen;
     r300screen->screen.get_name = r300_get_name;
diff --git a/src/gallium/drivers/r300/r300_screen.h b/src/gallium/drivers/r300/r300_screen.h
index f05fdcab469..6879c465b90 100644
--- a/src/gallium/drivers/r300/r300_screen.h
+++ b/src/gallium/drivers/r300/r300_screen.h
@@ -92,6 +92,8 @@ radeon_winsys(struct pipe_screen *screen) {
 #define DBG_NO_HIZ      (1 << 22)
 #define DBG_NO_CMASK    (1 << 23)
 #define DBG_NO_TCL      (1 << 25)
+#define DBG_IEEEMATH    (1 << 26)
+#define DBG_FFMATH      (1 << 27)
 /*@}*/
 static inline bool SCREEN_DBG_ON(struct r300_screen * screen, unsigned flags)
 {
diff --git a/src/gallium/drivers/r300/r300_vs.c b/src/gallium/drivers/r300/r300_vs.c
index 71915bb28fa..44303e6776a 100644
--- a/src/gallium/drivers/r300/r300_vs.c
+++ b/src/gallium/drivers/r300/r300_vs.c
@@ -198,6 +198,12 @@ void r300_translate_vertex_shader(struct r300_context *r300,
     compiler.Base.debug = &r300->context.debug;
     compiler.Base.is_r500 = r300->screen->caps.is_r500;
     compiler.Base.disable_optimizations = DBG_ON(r300, DBG_NO_OPT);
+    /* Only R500 has few IEEE math opcodes. */
+    if (r300->screen->options.ieeemath && r300->screen->caps.is_r500) {
+        compiler.Base.math_rules = RC_MATH_IEEE;
+    } else if (r300->screen->options.ffmath) {
+        compiler.Base.math_rules = RC_MATH_FF;
+    }
     compiler.Base.has_half_swizzles = false;
     compiler.Base.has_presub = false;
     compiler.Base.has_omod = false;