compiler: test float to int conversions and fix upper-bound calculation

compiler/compiler.go

@@ -2569,7 +2569,7 @@ func (b *builder) createConvert(typeFrom, typeTo types.Type, value llvm.Value, p
 				maxFloat := float64(max)
 				if bits.Len64(max) > significandBits {
 					// Round the max down to fit within the significand.
-					maxFloat = float64(max & ^uint64(0) << uint(bits.Len64(max)-significandBits))
+					maxFloat = float64(max & (^uint64(0) << uint(bits.Len64(max)-significandBits)))
 				}
 
 				// Check if the value is in-bounds (0 <= value <= max).
@@ -2598,7 +2598,7 @@ func (b *builder) createConvert(typeFrom, typeTo types.Type, value llvm.Value, p
 				maxFloat := float64(max)
 				if bits.Len64(max) > significandBits {
 					// Round the max down to fit within the significand.
-					maxFloat = float64(max & ^uint64(0) << uint(bits.Len64(max)-significandBits))
+					maxFloat = float64(max & (^uint64(0) << uint(bits.Len64(max)-significandBits)))
 				}
 
 				// Check if the value is in-bounds (min <= value <= max).
@@ -2609,10 +2609,17 @@ func (b *builder) createConvert(typeFrom, typeTo types.Type, value llvm.Value, p
 				// Assuming that the value is out-of-bounds, select a saturated value.
 				saturated := b.CreateSelect(aboveMin,
 					llvm.ConstInt(llvmTypeTo, max, false), // value > max
-					llvm.ConstInt(llvmTypeTo, min, false), // value < min (or NaN)
+					llvm.ConstInt(llvmTypeTo, min, false), // value < min
 					"saturated",
 				)
 
+				// Map NaN to 0.
+				saturated = b.CreateSelect(b.CreateFCmp(llvm.FloatUNO, value, value, "isnan"),
+					llvm.ConstNull(llvmTypeTo),
+					saturated,
+					"remapped",
+				)
+
 				// Do a normal conversion.
 				normal := b.CreateFPToSI(value, llvmTypeTo, "normal")
 

compiler/compiler_test.go

@@ -37,6 +37,7 @@ func TestCompiler(t *testing.T) {
 		"basic.go",
 		"pointer.go",
 		"slice.go",
+		"float.go",
 	}
 
 	for _, testCase := range tests {

compiler/testdata/float.go

@@ -0,0 +1,39 @@
+package main
+
+// Test converting floats to ints.
+
+func f32tou32(v float32) uint32 {
+	return uint32(v)
+}
+
+func maxu32f() float32 {
+	return float32(^uint32(0))
+}
+
+func maxu32tof32() uint32 {
+	f := float32(^uint32(0))
+	return uint32(f)
+}
+
+func inftoi32() (uint32, uint32, int32, int32) {
+	inf := 1.0
+	inf /= 0.0
+
+	return uint32(inf), uint32(-inf), int32(inf), int32(-inf)
+}
+
+func u32tof32tou32(v uint32) uint32 {
+	return uint32(float32(v))
+}
+
+func f32tou32tof32(v float32) float32 {
+	return float32(uint32(v))
+}
+
+func f32tou8(v float32) uint8 {
+	return uint8(v)
+}
+
+func f32toi8(v float32) int8 {
+	return int8(v)
+}

compiler/testdata/float.ll

@@ -0,0 +1,80 @@
+; ModuleID = 'float.go'
+source_filename = "float.go"
+target datalayout = "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-f64:32:64-f80:32-n8:16:32-S128"
+target triple = "i686--linux"
+
+define internal void @main.init(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret void
+}
+
+define internal i32 @main.f32tou32(float %v, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %positive = fcmp oge float %v, 0.000000e+00
+  %withinmax = fcmp ole float %v, 0x41EFFFFFC0000000
+  %inbounds = and i1 %positive, %withinmax
+  %saturated = sext i1 %positive to i32
+  %normal = fptoui float %v to i32
+  %0 = select i1 %inbounds, i32 %normal, i32 %saturated
+  ret i32 %0
+}
+
+define internal float @main.maxu32f(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret float 0x41F0000000000000
+}
+
+define internal i32 @main.maxu32tof32(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret i32 -1
+}
+
+define internal { i32, i32, i32, i32 } @main.inftoi32(i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  ret { i32, i32, i32, i32 } { i32 -1, i32 0, i32 2147483647, i32 -2147483648 }
+}
+
+define internal i32 @main.u32tof32tou32(i32 %v, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %0 = uitofp i32 %v to float
+  %withinmax = fcmp ole float %0, 0x41EFFFFFC0000000
+  %normal = fptoui float %0 to i32
+  %1 = select i1 %withinmax, i32 %normal, i32 -1
+  ret i32 %1
+}
+
+define internal float @main.f32tou32tof32(float %v, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %positive = fcmp oge float %v, 0.000000e+00
+  %withinmax = fcmp ole float %v, 0x41EFFFFFC0000000
+  %inbounds = and i1 %positive, %withinmax
+  %saturated = sext i1 %positive to i32
+  %normal = fptoui float %v to i32
+  %0 = select i1 %inbounds, i32 %normal, i32 %saturated
+  %1 = uitofp i32 %0 to float
+  ret float %1
+}
+
+define internal i8 @main.f32tou8(float %v, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %positive = fcmp oge float %v, 0.000000e+00
+  %withinmax = fcmp ole float %v, 2.550000e+02
+  %inbounds = and i1 %positive, %withinmax
+  %saturated = sext i1 %positive to i8
+  %normal = fptoui float %v to i8
+  %0 = select i1 %inbounds, i8 %normal, i8 %saturated
+  ret i8 %0
+}
+
+define internal i8 @main.f32toi8(float %v, i8* %context, i8* %parentHandle) unnamed_addr {
+entry:
+  %abovemin = fcmp oge float %v, -1.280000e+02
+  %belowmax = fcmp ole float %v, 1.270000e+02
+  %inbounds = and i1 %abovemin, %belowmax
+  %saturated = select i1 %abovemin, i8 127, i8 -128
+  %isnan = fcmp uno float %v, 0.000000e+00
+  %remapped = select i1 %isnan, i8 0, i8 %saturated
+  %normal = fptosi float %v to i8
+  %0 = select i1 %inbounds, i8 %normal, i8 %remapped
+  ret i8 %0
+}