From 57df511180ae015c4f6fac2a8260649a79e8ead9 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 19 May 2025 15:51:13 +0100 Subject: [PATCH] target/i386: Wire up MXCSR.DE and FPUS.DE correctly The x86 DE bit in the FPU and MXCSR status is supposed to be set when an input denormal is consumed. We didn't previously report this from softfloat, so the x86 code either simply didn't set the DE bit or else incorrectly wired it up to denormal_flushed, depending on which register you looked at. Now we have input_denormal_used we can wire up these DE bits with the semantics they are supposed to have. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Link: https://lore.kernel.org/r/20250519145114.2786534-4-peter.maydell@linaro.org Signed-off-by: Paolo Bonzini --- target/i386/tcg/fpu_helper.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/target/i386/tcg/fpu_helper.c b/target/i386/tcg/fpu_helper.c index 4732b71812..b3b23823fd 100644 --- a/target/i386/tcg/fpu_helper.c +++ b/target/i386/tcg/fpu_helper.c @@ -215,7 +215,7 @@ static void merge_exception_flags(CPUX86State *env, int old_flags) (new_flags & float_flag_overflow ? FPUS_OE : 0) | (new_flags & float_flag_underflow ? FPUS_UE : 0) | (new_flags & float_flag_inexact ? FPUS_PE : 0) | - (new_flags & float_flag_input_denormal_flushed ? FPUS_DE : 0))); + (new_flags & float_flag_input_denormal_used ? FPUS_DE : 0))); } static inline floatx80 helper_fdiv(CPUX86State *env, floatx80 a, floatx80 b) @@ -3254,6 +3254,7 @@ void update_mxcsr_status(CPUX86State *env) /* Set exception flags. */ set_float_exception_flags((mxcsr & FPUS_IE ? float_flag_invalid : 0) | + (mxcsr & FPUS_DE ? float_flag_input_denormal_used : 0) | (mxcsr & FPUS_ZE ? float_flag_divbyzero : 0) | (mxcsr & FPUS_OE ? float_flag_overflow : 0) | (mxcsr & FPUS_UE ? float_flag_underflow : 0) | @@ -3270,14 +3271,8 @@ void update_mxcsr_status(CPUX86State *env) void update_mxcsr_from_sse_status(CPUX86State *env) { int flags = get_float_exception_flags(&env->sse_status); - /* - * The MXCSR denormal flag has opposite semantics to - * float_flag_input_denormal_flushed (the softfloat code sets that flag - * only when flushing input denormals to zero, but SSE sets it - * only when not flushing them to zero), so is not converted - * here. - */ env->mxcsr |= ((flags & float_flag_invalid ? FPUS_IE : 0) | + (flags & float_flag_input_denormal_used ? FPUS_DE : 0) | (flags & float_flag_divbyzero ? FPUS_ZE : 0) | (flags & float_flag_overflow ? FPUS_OE : 0) | (flags & float_flag_underflow ? FPUS_UE : 0) | -- 2.39.5