HLSL-IR: fix frexp polyfill

The polyfill needed to maintain the sign of the fractional part, not
the exponent.

Bug: b/375407462
Change-Id: I140aaaba18602919deb7657d3aefea3bbcca7614
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/212735
Auto-Submit: Antonio Maiorano <[email protected]>
Reviewed-by: James Price <[email protected]>
Commit-Queue: James Price <[email protected]>

src/tint/lang/hlsl/writer/raise/builtin_polyfill.cc

@@ -1776,14 +1776,14 @@ struct State {
             auto* exp_out = b.Var(ty.ptr<function>(arg_ty));
             // HLSL frexp writes exponent part to second out param, and returns the fraction
             // (mantissa) part.
-            auto* call_result = b.Call<hlsl::ir::BuiltinCall>(arg_ty, hlsl::BuiltinFn::kFrexp, arg,
-                                                              b.Load(exp_out));
-            // The returned exponent is always positive, but for WGSL, we want it to keep the sign
+            core::ir::Instruction* fract = b.Call<hlsl::ir::BuiltinCall>(
+                arg_ty, hlsl::BuiltinFn::kFrexp, arg, b.Load(exp_out));
+            // The returned fraction is always positive, but for WGSL, we want it to keep the sign
             // of the input value.
             auto* arg_sign = BuildSign(arg);
-            b.Store(exp_out, b.Multiply(arg_ty, arg_sign, b.Load(exp_out)));
+            fract = b.Multiply(arg_ty, arg_sign, fract);
             // Replace the call with new result struct
-            b.ConstructWithResult(call->DetachResult(), call_result,
+            b.ConstructWithResult(call->DetachResult(), fract,
                                   b.Convert(arg_i32_ty, b.Load(exp_out)));
         });
         call->Destroy();

src/tint/lang/hlsl/writer/raise/builtin_polyfill_test.cc

@@ -7379,13 +7379,11 @@ __frexp_result_f32 = struct @align(4) {
     %6:f32 = hlsl.frexp %3, %5
     %7:i32 = hlsl.sign %3
     %8:f32 = convert %7
-    %9:f32 = load %4
-    %10:f32 = mul %8, %9
-    store %4, %10
-    %11:f32 = load %4
-    %12:i32 = convert %11
-    %13:__frexp_result_f32 = construct %6, %12
-    %a:__frexp_result_f32 = let %13
+    %9:f32 = mul %8, %6
+    %10:f32 = load %4
+    %11:i32 = convert %10
+    %12:__frexp_result_f32 = construct %9, %11
+    %a:__frexp_result_f32 = let %12
     ret
   }
 }
@@ -7437,13 +7435,11 @@ __frexp_result_vec3_f32 = struct @align(16) {
     %6:vec3<f32> = hlsl.frexp %3, %5
     %7:vec3<i32> = hlsl.sign %3
     %8:vec3<f32> = convert %7
-    %9:vec3<f32> = load %4
-    %10:vec3<f32> = mul %8, %9
-    store %4, %10
-    %11:vec3<f32> = load %4
-    %12:vec3<i32> = convert %11
-    %13:__frexp_result_vec3_f32 = construct %6, %12
-    %a:__frexp_result_vec3_f32 = let %13
+    %9:vec3<f32> = mul %8, %6
+    %10:vec3<f32> = load %4
+    %11:vec3<i32> = convert %10
+    %12:__frexp_result_vec3_f32 = construct %9, %11
+    %a:__frexp_result_vec3_f32 = let %12
     ret
   }
 }

test/tint/builtins/frexp/scalar/mixed.wgsl.expected.ir.dxc.hlsl

@@ -10,9 +10,8 @@ void main() {
   frexp_result_f32 res = {0.625f, int(1)};
   float v = 0.0f;
   float v_1 = frexp(runtime_in, v);
-  float v_2 = float(sign(runtime_in));
-  v = (v_2 * v);
-  frexp_result_f32 v_3 = {v_1, int(v)};
+  float v_2 = (float(sign(runtime_in)) * v_1);
+  frexp_result_f32 v_3 = {v_2, int(v)};
   res = v_3;
   frexp_result_f32 v_4 = {0.625f, int(1)};
   res = v_4;

test/tint/builtins/frexp/scalar/mixed.wgsl.expected.ir.fxc.hlsl

@@ -10,9 +10,8 @@ void main() {
   frexp_result_f32 res = {0.625f, int(1)};
   float v = 0.0f;
   float v_1 = frexp(runtime_in, v);
-  float v_2 = float(sign(runtime_in));
-  v = (v_2 * v);
-  frexp_result_f32 v_3 = {v_1, int(v)};
+  float v_2 = (float(sign(runtime_in)) * v_1);
+  frexp_result_f32 v_3 = {v_2, int(v)};
   res = v_3;
   frexp_result_f32 v_4 = {0.625f, int(1)};
   res = v_4;

test/tint/builtins/frexp/scalar/runtime.wgsl.expected.ir.dxc.hlsl

@@ -9,9 +9,8 @@ void main() {
   float tint_symbol = 1.25f;
   float v = 0.0f;
   float v_1 = frexp(tint_symbol, v);
-  float v_2 = float(sign(tint_symbol));
-  v = (v_2 * v);
-  frexp_result_f32 res = {v_1, int(v)};
+  float v_2 = (float(sign(tint_symbol)) * v_1);
+  frexp_result_f32 res = {v_2, int(v)};
   float fract = res.fract;
   int exp = res.exp;
 }

test/tint/builtins/frexp/scalar/runtime.wgsl.expected.ir.fxc.hlsl

@@ -9,9 +9,8 @@ void main() {
   float tint_symbol = 1.25f;
   float v = 0.0f;
   float v_1 = frexp(tint_symbol, v);
-  float v_2 = float(sign(tint_symbol));
-  v = (v_2 * v);
-  frexp_result_f32 res = {v_1, int(v)};
+  float v_2 = (float(sign(tint_symbol)) * v_1);
+  frexp_result_f32 res = {v_2, int(v)};
   float fract = res.fract;
   int exp = res.exp;
 }

test/tint/builtins/frexp/vector/mixed.wgsl.expected.ir.dxc.hlsl

@@ -10,9 +10,8 @@ void main() {
   frexp_result_vec2_f32 res = {float2(0.625f, 0.9375f), int2(int(1), int(2))};
   float2 v = (0.0f).xx;
   float2 v_1 = frexp(runtime_in, v);
-  float2 v_2 = float2(sign(runtime_in));
-  v = (v_2 * v);
-  frexp_result_vec2_f32 v_3 = {v_1, int2(v)};
+  float2 v_2 = (float2(sign(runtime_in)) * v_1);
+  frexp_result_vec2_f32 v_3 = {v_2, int2(v)};
   res = v_3;
   frexp_result_vec2_f32 v_4 = {float2(0.625f, 0.9375f), int2(int(1), int(2))};
   res = v_4;

test/tint/builtins/frexp/vector/mixed.wgsl.expected.ir.fxc.hlsl

@@ -10,9 +10,8 @@ void main() {
   frexp_result_vec2_f32 res = {float2(0.625f, 0.9375f), int2(int(1), int(2))};
   float2 v = (0.0f).xx;
   float2 v_1 = frexp(runtime_in, v);
-  float2 v_2 = float2(sign(runtime_in));
-  v = (v_2 * v);
-  frexp_result_vec2_f32 v_3 = {v_1, int2(v)};
+  float2 v_2 = (float2(sign(runtime_in)) * v_1);
+  frexp_result_vec2_f32 v_3 = {v_2, int2(v)};
   res = v_3;
   frexp_result_vec2_f32 v_4 = {float2(0.625f, 0.9375f), int2(int(1), int(2))};
   res = v_4;

test/tint/builtins/frexp/vector/runtime.wgsl.expected.ir.dxc.hlsl

@@ -9,9 +9,8 @@ void main() {
   float2 tint_symbol = float2(1.25f, 3.75f);
   float2 v = (0.0f).xx;
   float2 v_1 = frexp(tint_symbol, v);
-  float2 v_2 = float2(sign(tint_symbol));
-  v = (v_2 * v);
-  frexp_result_vec2_f32 res = {v_1, int2(v)};
+  float2 v_2 = (float2(sign(tint_symbol)) * v_1);
+  frexp_result_vec2_f32 res = {v_2, int2(v)};
   float2 fract = res.fract;
   int2 exp = res.exp;
 }

test/tint/builtins/frexp/vector/runtime.wgsl.expected.ir.fxc.hlsl

@@ -9,9 +9,8 @@ void main() {
   float2 tint_symbol = float2(1.25f, 3.75f);
   float2 v = (0.0f).xx;
   float2 v_1 = frexp(tint_symbol, v);
-  float2 v_2 = float2(sign(tint_symbol));
-  v = (v_2 * v);
-  frexp_result_vec2_f32 res = {v_1, int2(v)};
+  float2 v_2 = (float2(sign(tint_symbol)) * v_1);
+  frexp_result_vec2_f32 res = {v_2, int2(v)};
   float2 fract = res.fract;
   int2 exp = res.exp;
 }

test/tint/builtins/gen/var/frexp/3dd21e.wgsl.expected.ir.dxc.hlsl

@@ -17,9 +17,8 @@ void frexp_3dd21e() {
   vector<float16_t, 4> v = arg_0;
   vector<float16_t, 4> v_1 = (float16_t(0.0h)).xxxx;
   vector<float16_t, 4> v_2 = frexp(v, v_1);
-  vector<float16_t, 4> v_3 = vector<float16_t, 4>(sign(v));
-  v_1 = (v_3 * v_1);
-  frexp_result_vec4_f16 res = {v_2, int4(v_1)};
+  vector<float16_t, 4> v_3 = (vector<float16_t, 4>(sign(v)) * v_2);
+  frexp_result_vec4_f16 res = {v_3, int4(v_1)};
 }
 
 void fragment_main() {

test/tint/builtins/gen/var/frexp/4b2200.wgsl.expected.ir.dxc.hlsl

@@ -17,9 +17,8 @@ void frexp_4b2200() {
   float v = arg_0;
   float v_1 = 0.0f;
   float v_2 = frexp(v, v_1);
-  float v_3 = float(sign(v));
-  v_1 = (v_3 * v_1);
-  frexp_result_f32 res = {v_2, int(v_1)};
+  float v_3 = (float(sign(v)) * v_2);
+  frexp_result_f32 res = {v_3, int(v_1)};
 }
 
 void fragment_main() {

test/tint/builtins/gen/var/frexp/4b2200.wgsl.expected.ir.fxc.hlsl

@@ -17,9 +17,8 @@ void frexp_4b2200() {
   float v = arg_0;
   float v_1 = 0.0f;
   float v_2 = frexp(v, v_1);
-  float v_3 = float(sign(v));
-  v_1 = (v_3 * v_1);
-  frexp_result_f32 res = {v_2, int(v_1)};
+  float v_3 = (float(sign(v)) * v_2);
+  frexp_result_f32 res = {v_3, int(v_1)};
 }
 
 void fragment_main() {

test/tint/builtins/gen/var/frexp/5257dd.wgsl.expected.ir.dxc.hlsl

@@ -17,9 +17,8 @@ void frexp_5257dd() {
   float16_t v = arg_0;
   float16_t v_1 = float16_t(0.0h);
   float16_t v_2 = frexp(v, v_1);
-  float16_t v_3 = float16_t(sign(v));
-  v_1 = (v_3 * v_1);
-  frexp_result_f16 res = {v_2, int(v_1)};
+  float16_t v_3 = (float16_t(sign(v)) * v_2);
+  frexp_result_f16 res = {v_3, int(v_1)};
 }
 
 void fragment_main() {

test/tint/builtins/gen/var/frexp/5f47bf.wgsl.expected.ir.dxc.hlsl

@@ -17,9 +17,8 @@ void frexp_5f47bf() {
   vector<float16_t, 2> v = arg_0;
   vector<float16_t, 2> v_1 = (float16_t(0.0h)).xx;
   vector<float16_t, 2> v_2 = frexp(v, v_1);
-  vector<float16_t, 2> v_3 = vector<float16_t, 2>(sign(v));
-  v_1 = (v_3 * v_1);
-  frexp_result_vec2_f16 res = {v_2, int2(v_1)};
+  vector<float16_t, 2> v_3 = (vector<float16_t, 2>(sign(v)) * v_2);
+  frexp_result_vec2_f16 res = {v_3, int2(v_1)};
 }
 
 void fragment_main() {

test/tint/builtins/gen/var/frexp/77af93.wgsl.expected.ir.dxc.hlsl

@@ -17,9 +17,8 @@ void frexp_77af93() {
   float4 v = arg_0;
   float4 v_1 = (0.0f).xxxx;
   float4 v_2 = frexp(v, v_1);
-  float4 v_3 = float4(sign(v));
-  v_1 = (v_3 * v_1);
-  frexp_result_vec4_f32 res = {v_2, int4(v_1)};
+  float4 v_3 = (float4(sign(v)) * v_2);
+  frexp_result_vec4_f32 res = {v_3, int4(v_1)};
 }
 
 void fragment_main() {

test/tint/builtins/gen/var/frexp/77af93.wgsl.expected.ir.fxc.hlsl

@@ -17,9 +17,8 @@ void frexp_77af93() {
   float4 v = arg_0;
   float4 v_1 = (0.0f).xxxx;
   float4 v_2 = frexp(v, v_1);
-  float4 v_3 = float4(sign(v));
-  v_1 = (v_3 * v_1);
-  frexp_result_vec4_f32 res = {v_2, int4(v_1)};
+  float4 v_3 = (float4(sign(v)) * v_2);
+  frexp_result_vec4_f32 res = {v_3, int4(v_1)};
 }
 
 void fragment_main() {

test/tint/builtins/gen/var/frexp/979800.wgsl.expected.ir.dxc.hlsl

@@ -17,9 +17,8 @@ void frexp_979800() {
   float3 v = arg_0;
   float3 v_1 = (0.0f).xxx;
   float3 v_2 = frexp(v, v_1);
-  float3 v_3 = float3(sign(v));
-  v_1 = (v_3 * v_1);
-  frexp_result_vec3_f32 res = {v_2, int3(v_1)};
+  float3 v_3 = (float3(sign(v)) * v_2);
+  frexp_result_vec3_f32 res = {v_3, int3(v_1)};
 }
 
 void fragment_main() {

test/tint/builtins/gen/var/frexp/979800.wgsl.expected.ir.fxc.hlsl

@@ -17,9 +17,8 @@ void frexp_979800() {
   float3 v = arg_0;
   float3 v_1 = (0.0f).xxx;
   float3 v_2 = frexp(v, v_1);
-  float3 v_3 = float3(sign(v));
-  v_1 = (v_3 * v_1);
-  frexp_result_vec3_f32 res = {v_2, int3(v_1)};
+  float3 v_3 = (float3(sign(v)) * v_2);
+  frexp_result_vec3_f32 res = {v_3, int3(v_1)};
 }
 
 void fragment_main() {

test/tint/builtins/gen/var/frexp/ae4a66.wgsl.expected.ir.dxc.hlsl

@@ -17,9 +17,8 @@ void frexp_ae4a66() {
   vector<float16_t, 3> v = arg_0;
   vector<float16_t, 3> v_1 = (float16_t(0.0h)).xxx;
   vector<float16_t, 3> v_2 = frexp(v, v_1);
-  vector<float16_t, 3> v_3 = vector<float16_t, 3>(sign(v));
-  v_1 = (v_3 * v_1);
-  frexp_result_vec3_f16 res = {v_2, int3(v_1)};
+  vector<float16_t, 3> v_3 = (vector<float16_t, 3>(sign(v)) * v_2);
+  frexp_result_vec3_f16 res = {v_3, int3(v_1)};
 }
 
 void fragment_main() {

test/tint/builtins/gen/var/frexp/eb2421.wgsl.expected.ir.dxc.hlsl

@@ -17,9 +17,8 @@ void frexp_eb2421() {
   float2 v = arg_0;
   float2 v_1 = (0.0f).xx;
   float2 v_2 = frexp(v, v_1);
-  float2 v_3 = float2(sign(v));
-  v_1 = (v_3 * v_1);
-  frexp_result_vec2_f32 res = {v_2, int2(v_1)};
+  float2 v_3 = (float2(sign(v)) * v_2);
+  frexp_result_vec2_f32 res = {v_3, int2(v_1)};
 }
 
 void fragment_main() {

test/tint/builtins/gen/var/frexp/eb2421.wgsl.expected.ir.fxc.hlsl

@@ -17,9 +17,8 @@ void frexp_eb2421() {
   float2 v = arg_0;
   float2 v_1 = (0.0f).xx;
   float2 v_2 = frexp(v, v_1);
-  float2 v_3 = float2(sign(v));
-  v_1 = (v_3 * v_1);
-  frexp_result_vec2_f32 res = {v_2, int2(v_1)};
+  float2 v_3 = (float2(sign(v)) * v_2);
+  frexp_result_vec2_f32 res = {v_3, int2(v_1)};
 }
 
 void fragment_main() {