From 8e99c3313bee8d3dd15ccf476321070d7da8ee81 Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Thu, 10 Jan 2019 14:09:04 +0100
Subject: [PATCH] compiler: fix make([]T, ...) with big integers on 32-bit
 systems or less

Previously, this would have resulted in a LLVM verification error
because runtime.sliceBoundsCheckMake would not accept 64-bit integers on
these platforms.
---
 compiler/compiler.go | 24 +++++++++++++++++-------
 src/runtime/panic.go |  7 +++++++
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/compiler/compiler.go b/compiler/compiler.go
index cf5a61c6..625dcc77 100644
--- a/compiler/compiler.go
+++ b/compiler/compiler.go
@@ -1730,21 +1730,31 @@ func (c *Compiler) parseExpr(frame *Frame, expr ssa.Value) (llvm.Value, error) {
 
 		// Bounds checking.
 		if !frame.fn.IsNoBounds() {
-			if sliceLen.Type().IntTypeWidth() < c.uintptrType.IntTypeWidth() {
+			checkFunc := "sliceBoundsCheckMake"
+			biggestInt := c.uintptrType
+			biggestIntWidth := biggestInt.IntTypeWidth()
+			if sliceLen.Type().IntTypeWidth() > biggestIntWidth || sliceCap.Type().IntTypeWidth() > biggestIntWidth {
+				// System that is less than 64bit, meaning that the slice make
+				// params are bigger than uintptr.
+				checkFunc = "sliceBoundsCheckMake64"
+				biggestInt = c.ctx.Int64Type()
+				biggestIntWidth = biggestInt.IntTypeWidth()
+			}
+			if sliceLen.Type().IntTypeWidth() < biggestIntWidth {
 				if expr.Len.Type().(*types.Basic).Info()&types.IsUnsigned != 0 {
-					sliceLen = c.builder.CreateZExt(sliceLen, c.uintptrType, "")
+					sliceLen = c.builder.CreateZExt(sliceLen, biggestInt, "")
 				} else {
-					sliceLen = c.builder.CreateSExt(sliceLen, c.uintptrType, "")
+					sliceLen = c.builder.CreateSExt(sliceLen, biggestInt, "")
 				}
 			}
-			if sliceCap.Type().IntTypeWidth() < c.uintptrType.IntTypeWidth() {
+			if sliceCap.Type().IntTypeWidth() < biggestIntWidth {
 				if expr.Cap.Type().(*types.Basic).Info()&types.IsUnsigned != 0 {
-					sliceCap = c.builder.CreateZExt(sliceCap, c.uintptrType, "")
+					sliceCap = c.builder.CreateZExt(sliceCap, biggestInt, "")
 				} else {
-					sliceCap = c.builder.CreateSExt(sliceCap, c.uintptrType, "")
+					sliceCap = c.builder.CreateSExt(sliceCap, biggestInt, "")
 				}
 			}
-			c.createRuntimeCall("sliceBoundsCheckMake", []llvm.Value{sliceLen, sliceCap}, "")
+			c.createRuntimeCall(checkFunc, []llvm.Value{sliceLen, sliceCap}, "")
 		}
 
 		// Allocate the backing array.
diff --git a/src/runtime/panic.go b/src/runtime/panic.go
index e00ec2fe..9140fcd0 100644
--- a/src/runtime/panic.go
+++ b/src/runtime/panic.go
@@ -62,3 +62,10 @@ func sliceBoundsCheckMake(length, capacity uint) {
 		runtimePanic("slice size out of range")
 	}
 }
+
+// Check for bounds in *ssa.MakeSlice. Supports 64-bit indexes.
+func sliceBoundsCheckMake64(length, capacity uint64) {
+	if !(0 <= length && length <= capacity) {
+		runtimePanic("slice size out of range")
+	}
+}